WASHINGTON (AP) - The Latest on the 2016 presidential campaign (all times Eastern Daylight Time):
Mitt Romney is keeping up the pressure on Donald Trump to release his tax returns.
The 2012 GOP presidential nominee is suggesting the real reason Trump is not releasing his tax returns is that the billionaire is hiding "a bombshell of unusual size" in the documents.
The accusation came in a pointed Facebook post Wednesday as likely Democratic presidential candidate Hillary Clinton slammed Trump over the transparency issue.
Trump said in an AP interview Tuesday that he doesn't believe he has an obligation to release his tax returns and won't release them before November - unless an ongoing audit of his finances is completed before Election Day. He said he wouldn't overrule his lawyers and instruct them to release his returns if the audit hasn't concluded by then.
Romney called any refusal by Trump to release his tax returns before Election Day, "disqualifying."
It has become tradition over the last three decades for presidential nominees in both parties to release their returns.
Donald Trump has booked his first campaign fund-raiser, to take place in two weeks in Los Angeles.
That's according to Steven Mnuchin, Trump's newly named national finance chairman. Mnuchin would not share details of the event, but he tells The Associated Press that he's had a "very good reception" and that it will be hosted by a "high-profile" donor.
Mnuchin says more fundraising details will soon be announced, including the names of state- and regional-level fund-raisers. He says the campaign and Republican Party are "very, very close" to inking a joint fund-raising deal.
Mnuchin spoke with the AP in Las Vegas, where he's attending a financial industry conference hosted by Anthony Scaramucci. Scaramucci last week told The AP he'd signed on with Trump's fund-raising team.
T. Boone Pickens, a billionaire oil investor, is feeling bullish about presidential candidate Donald Trump.
He says it's time to "try somebody different" as the GOP presidential nominee, whose unorthodox bid has given other major GOP donors pause.
Pickens, one of the party's most prolific donors, says Trump called him on Monday and the two had a chuckle about how he'd given big money to GOP rivals Jeb Bush and Carly Fiorina before Trump beat them.
Pickens says he told Trump he's with him now.
The blunt-talking 87-year-old says he would contribute to Trump and likely to a pro-Trump super PAC, as well, although he says is too early to put a dollar amount on it.
Pickens made the comments Wednesday at the SALT conference, an annual gathering of financial industry leaders held in Las Vegas.
Pickens says he agrees with one of Trump's more controversial plans, to temporarily ban Muslims from entering the country.
GOP Senator Charles Grassley of Iowa says he doesn't believe Donald Trump would try to pay America's creditors less than full value on the government debt they hold, as the presidential candidate last week suggested.
Grassley told reporters Wednesday that when Trump is president, "he won't pursue that policy."
When asked how he knew that, Grassley said the United States' "credibility and credit is very important" to the country and the world. He declined to answer whether Trump's idea would undermine that.
The presumptive Republican presidential nominee suggested recently that he would buy U.S. debt back at a discount from investors in hopes of refinancing them at lower rates. Economic experts have criticized the idea, arguing it would send rates soaring, slow economic growth and undermine confidence in the world's most trusted financial asset.
Trump later backed off that claim, indicating that the government could avoid default by printing money. This proposed strategy would likely spark inflation, economists have said.
Sen. Elizabeth Warren has taken to Twitter again to bash Donald Trump. It's the latest in a series of Internet "tweetstorms" calling Trump on the carpet for his treatment of women and his insults toward her.
The Massachusetts Democrat has far fewer followers than Trump and she is a cleaner Twitter fighter than the billionaire. But she is scrappy.
In her latest volley, she tweets: "Your policies are dangerous. Your words are reckless. Your record is embarrassing. And your free ride is over."
This followed a couple of anti-Warren tweets lobbed by Trump.
Says one: "Goofy Elizabeth Warren has been one of the least effective senators in the entire U.S. Senate. She has done nothing!"
Hillary Clinton says Donald Trump's tax agenda was "written by a billionaire for billionaires" and will benefit the wealthy at the expense of middle-class workers.
Clinton says in Blackwood, New Jersey, that Trump would add trillions to the debt in exchange for tax cuts for people earning more than $1 million a year.
The Democratic presidential candidate says Trump should also release his tax returns. The Republican candidate told The Associated Press in an interview that he doesn't plan to do that until an audit of his finances is complete. And he doesn't expect that to be before November.
Clinton says releasing tax returns is "kind of expected" by the presidential nominees of each party and she notes she has put out more than three decades of returns.
West Virginia's tricky primary rules could cost Donald Trump four delegates. It won't matter - Trump has 92 percent of the delegates needed to win the nomination.
But it illustrates the whacky ways in which some states award convention delegates.
Trump easily won the West Virginia primary. However, most of the state's delegates are elected directly by voters.
Twenty-two delegates were elected based on the statewide vote, and the top 22 vote getters were all Trump delegates. However, no more than two can be from the same county.
Trump had 13 from one county and three from another. As a result, he will get 30 of the state's 34 delegates. Three are uncommitted and one went to Ohio Gov. John Kasich.
Trump has 1,134 delegates. He needs 1,237 to win.
Bernie Sanders is trailing Hillary Clinton by 283 delegates.
He won West Virginia on Tuesday, but was only able to close the gap by seven delegates.
With 29 delegates at stake, Sanders won 18 to Clinton's 11.
That means based on primaries and caucuses to date, Clinton now has 1,716 and Sanders has 1,433.
He still needs to win 66 percent of the remaining primary and caucus delegates if he hopes to close the deficit.
When including superdelegates, or party officials who can back any candidate, Clinton holds a much wider lead.
She has 2,240 to Sanders' 1,473.
Just 143 delegates short, Clinton remains on track to reach the 2,383 needed to win the nomination by early next month.
House Speaker Paul Ryan says the Republican Party needs to be unified to defeat Democrat Hillary Clinton in the November election.
Ryan spoke to reporters Wednesday morning ahead of his Thursday meeting with presumptive Republican presidential nominee Donald Trump. Ryan stunned the GOP last week when he said he wasn't ready to endorse the billionaire businessman.
Ryan said the party needs a "real unification" and must be at full strength to win the presidential election.
The speaker has faced some criticism for his reluctance to embrace Trump's candidacy.
Donald Trump says he may set up a commission to study his immigration policies and his proposed ban on foreign Muslims entering the U.S. The man he may ask to lead the commission is the former New York mayor, Rudy Giuliani, who's called Trump's idea of a Muslim ban unconstitutional.
Trump floated the idea of a commission Wednesday on Fox News and addressed it only briefly, not saying if this would happen if he wins the White House or during his Republican presidential campaign.
Trump's call to deny entry to Muslims from abroad until America's security has been assured is a centerpiece of his campaign. So are his proposals to deport all people who are in the country illegally.
He says a commission would examine all those issues, as well as the question of letting in Syrian refugees, and it would be "possibly headed" by Giuliani, the mayor when New York was attacked on 9/11.
Giuliani said in December that Syrian refugees should not be let in. But he said a ban on Muslims would violate the Constitution and there can be no religious test on who is allowed into the country.
Donald Trump has won nearly the all the delegates who were at stake in the West Virginia and Nebraska primaries.
Overall, Trump now has 1,135 delegates, 92 percent of what he needs for the Republican presidential nomination.
He won all 36 delegates in Nebraska in Tuesday's contest and 31 of the 34 delegates at stake in West Virginia.
West Virginia's complicated rules could cost him the other three, who are uncommitted. In West Virginia, most of the delegates are elected directly by voters.
Twenty-two delegates are elected according to the statewide vote. However, no more than two delegates can be from the same county.
Thirteen Trump delegates ran from Kanawha County, home to Charleston, the state capital.
Florida Sen. Marco Rubio says he'll live up to his pledge to the Republican Party to support the GOP's presidential nominee. But that doesn't appear to mean he will campaign on behalf of Donald Trump.
Rubio says he still has the same deep reservations about Trump's ideas and conduct that he voiced as his rival in the primary campaign. He says Trump would be better served by having help in the campaign from people who agree with his policies and are enthusiastic about his candidacy.
Rubio is clearly not enthusiastic about Trump at all. But he says Democrat Hillary Clinton will be a worse choice in the fall campaign. The senator says he's "even more scared about her being in control of the U.S. government."
Donald Trump says he understands why the Bush family "is sitting out" the Republican presidential campaign.
Trump says he doesn't have the support of former candidate Jeb Bush because "I hit him really hard." Even so, he says it was "dishonorable" of Bush to back out of a pledge to support the party's nominee.
Former presidents George W. Bush and George H.W. Bush have also declined to back Trump.
Trump spoke Wednesday morning on Fox News Channel's "Fox & Friends."
A key House Republican is brushing aside talk of a possible third-party candidacy in the presidential election campaign.
Rep. Tom Cole of Oklahoma says it's awfully late for anybody to make such a move. There have been rumblings of a possible independent bid organized by conservative Republicans who don't like Donald Trump.
But Cole, who is deputy whip for House Republicans, says on MSNBC's "Morning Joe" he thinks such an effort would be a waste of time. And he says a third-party effort from the political right would probably ensure that Democrat Hillary Clinton becomes president.