Anguished Republicans wrestle with whether to support Trump

By Ginger Gibson and Emily Stephenson

(Reuters) - Republican lawmakers, operatives and donors grappled with whether to support Donald Trump, who effectively clinched his party's nomination this week after the departure of his two remaining rivals, Ted Cruz and John Kasich.

As Trump sought to rally the fractured party behind him, many prominent Republicans got behind the reality TV star and real estate developer, while some weighed their options. Still others said they might vote in the Nov. 8 general election for Hillary Clinton, the likely Democratic nominee.

Bill Achtmeyer, the Boston-based founder of consulting firm Parthenon Group, was among those weighing a possible for vote for Clinton.

"If she is able to move to the centre and think as creatively and thoughtfully as her husband did... boy, I would have a very hard time, based on what I know today, not voting for Hillary versus what Trump is espousing," said Achtmeyer, who has donated $200,000 to Republicans over the last decade.

Another Republican donor, David Beightol, a Washington lobbyist who raised money this year for the presidential bid of former Florida Governor Jeb Bush, said he was leaning towards voting for Trump because he could not support Clinton.

"I'm not there yet, but I don't have a lot of choice," Beightol said.

In most U.S. elections cycles, party insiders quickly coalesce around candidates once they have effectively sewn up the nomination. But Trump's bombastic rhetoric, unorthodox campaign and his lack of experience in government have left the party divided.

Trump has vowed to deport illegal immigrants and build a wall along the Mexican border. He also said he would temporarily bar Muslims from entering the country as a way to combat terrorism.

Republican former presidents George H.W. Bush and George W. Bush do not plan to endorse anyone in the White House race this year, their spokesmen told the Texas Tribune.

On Wednesday, fresh off the win in Indiana's primary that drove both his rivals out of the race, Trump pledged to unify the party and said he was getting calls from people who had criticized him in the past but now wanted to back him.Trump supporters said he could ease concerns about his lack of experience by choosing a well-known running mate. Representatives Scott DesJarlais of Tennessee and Chris Collins of New York both suggested former U.S. Secretary of State Condoleezza Rice.

Rice could not be reached immediately for comment.

Backers also said Trump could mend ties with allies of Cruz, who had been his strongest challenger and had trumpeted himself as a true conservative, by meeting with lawmakers in person after a heated campaign in which Trump dubbed his rival "Lyin' Ted."

Cruz's supporters on Capitol Hill have ties to conservative activists and the Tea Party, groups that could help Trump raise money and turn out voters. DesJarlais said meeting Trump in person would improve their impressions of him.

Representative Raul Labrador, a Cruz backer and conservative leader from Idaho, told a radio station he saw Trump as favouring the political "establishment" even though he ran as an outsider. But he said Trump would likely appoint a conservative to the U.S. Supreme Court, a priority for many on the political right.

"With Clinton, there is no chance," Labrador said. "In my opinion, there's just no choice between the two."

(Reporting by Emily Stephenson, Ginger Gibson and Susan Cornwell; Additional reporting by Grant Smith and Sharon Bernstein; Editing by Leslie Adler)