With fresh momentum, Trump tells GOP to embrace his bid

(AP) — His party in chaos, a surging Donald Trump called on mainstream Republicans to unify behind his candidacy on Wednesday as his White House rivals seized on their last best opportunity to block the billionaire businessman from building an insurmountable delegate lead in two key states.

Cruz intensified his own bid to blunt Trump's momentum, unveiling on Wednesday an endorsement from former rival, retired business executive Carly Fiorina, who offers Cruz an immediate dose of credibility with his party's skeptical donor class.

[...] Tuesday's contests in Michigan, Mississippi, Idaho and Hawaii signaled bad news for Republican officials across the country who fear that both Trump and Cruz — the day's only GOP winners — are wholly unelectable in a general election.

While Fiorina's endorsement was noteworthy, many Republican leaders hoped Rubio would emerge as the face of the party given his ability to expand the GOP's appeal beyond its traditional base of older, white men.

"The Republican establishment is in its death throes," said longtime tea party leader Mark Meckler.

Desperately trying to put the focus back on Clinton, the Republican National Committee on Wednesday filed a federal lawsuit against the Obama administration to force the release of additional communication between Clinton's State Department, her campaign and senior aides.

"If this administration claims to be the 'most transparent in history,' and Clinton the 'most transparent person in public life,' then they should prove it, release these records, and allow the American people to hold her accountable," RNC chairman Reince Priebus said.