Trump is under pressure to professionalize his campaign beyond a close-knit group of advisers and expand the appeal of his anti-establishment candidacy in the face of fierce opposition from rival U.S. Senator Ted Cruz of Texas and a well-funded anti-Trump operation run by establishment Republicans.
Trump announced he had hired Rick Wiley as his national political director. Wiley, a long-time Republican strategist, had been campaign manager for Scott Walker, the Wisconsin governor who dropped out of the presidential race last autumn.
"He brings decades of experience, and his deep ties to political leaders and activists across the country will be a tremendous asset as we enter the final phase of securing the nomination," Trump said in a statement.
In addition, Trump's campaign arranged a meeting in Washington of about a dozen U.S. legislators as the fierce anti-establishment candidate tries to build more relationships inside Washington and broaden his appeal.
The meeting with the lawmakers and senior Trump adviser Ed Brookover is planned for Thursday morning on Capitol Hill, congressional aides said.
About a dozen lawmakers are expected to attend, some of whom have endorsed Trump and some of whom have not but who are interested in his message. Trump will not be there.
A series of policy speeches Trump plans to begin delivering soon could be among the topics discussed, one source said.
"They're definitely planning several policy speeches ... and they are looking for input on those," a Republican source familiar with the situation said.
KELLY: "CHANCE TO CLEAR THE AIR"
The Trump campaign received some good news when Politico reported that campaign manager Corey Lewandowski, who was charged last month in Florida with battery on a reporter, will not be prosecuted.
Palm Beach County State Attorney David Aronberg is scheduled to announce the decision not to press charges on Thursday afternoon, Politico reported, citing sources with knowledge of the situation.
In another development, Trump met privately at Trump Tower in New York with Fox News anchor Megyn Kelly after months of attacking her for the tough questions she asked him at a Republican debate last August about his treatment of women.
Tensions between Trump and Kelly, and controversial remarks he has made about abortion, have contributed to Trump's negative image with women. Opinion polls show the New York billionaire is viewed unfavorably by women by a wide margin.
Kelly said on her Fox News show she had asked for the meeting and used it to request an interview. "We met for about an hour just the two of us and had a chance to clear the air," she said.
In recent days Trump has attempted to soften his image with important constituencies such as female voters.
A group interview on CNN on Tuesday night featured Trump, his wife, Melania, daughter Ivanka and sons Eric and Donald Jr., and showed a more personal side to the often-brusque businessman.
Melania Trump said she had fussed at Trump to stop tweeting at night. "If he would only listen," she said, chuckling.
PROSPECT OF CONTESTED CONVENTION
Republican strategist Ron Bonjean said the hiring of Wiley and, two weeks ago, of delegate specialist Paul Manafort suggest that Trump is preparing for a contested convention in July should he not win outright the 1,237 delegates needed for the Republican presidential nomination.
"Without having good people on your team who understand how to navigate those waters, you're in big trouble," he said.
The steps point to a new phase of Trump's campaign after vulnerabilities were exposed when he was beaten in Wisconsin by Cruz and outmaneuvered by Cruz in the competition for delegates in Colorado.
As the Trump campaign attempts to get a better handle on the complicated delegate selection process, Trump is expected to send a contingent to a Republican National Committee (RNC) meeting in Florida next week.
Trump has been in a war of words with the RNC, accusing the party apparatus of having rules that, for example, allowed party regulars in Colorado to select delegates without giving Republicans there a chance to vote.
Trump on Tuesday said that RNC Chairman Reince Priebus "should be ashamed of himself."
Priebus, who met Trump two weeks ago at RNC headquarters in Washington, said the delegate-selection rules have been in place for a year and it is the responsibility of each campaign to understand them.
"Complaints now? Give us all a break," Priebus tweeted.