GOP begins bowing to the inevitable as Trump wins 2 more

Key Senate Republicans voiced optimism on Tuesday about Donald Trump's presidential prospects in November after Trump added two more primaries to his column, taking West Virginia and Nebraska.

This was the clearest signal yet to the GOP rank and file to unite behind the bombastic billionaire and turn their energy against Democrat Hillary Clinton. But it was uncertain whether the doubters could be quieted.

''We have a nominee, it looks like he may well be very competitive, and we want to win the White House,'' Senate Majority Leader Mitch McConnell told reporters. He also said, ''We know that Hillary Clinton will be four more years of Barack Obama. I think that's going to in the end be enough to unify Republicans across the country.''

Still, doubt and angst over Trump remained palpable as GOP lawmakers returned from a week-long recess that saw him effectively clinch the presidential nomination. For some, the question of whether they were backing their party's standard-bearer – a no-brainer in a normal election year – proved too much to answer.

''We're not doing any Trump questions today,'' an aide to Sen Mark Kirk of Illinois told a crowd of reporters as Kirk, one of the most endangered Senate Republicans, sped into a meeting.

Another Republican who's up for re-election, Tim Scott of South Carolina, offered his support, but like others managed to sound grudging and backhanded in the process. ''I'm supporting the Republican candidate, and it happens to be Donald Trump,'' he said.

A third, Sen Johnny Isakson of Georgia, deflected questions about whether he would back Trump, saying he's focused only on securing another six-year Senate term.

''The only thing I can do is get re-elected so we have a Republican majority in the Senate,'' Isakson said. ''I will support the Republican ticket and I'm endorsing me for my Senate seat.''

The comments reflected ongoing divisions in a party still reeling over Trump's success in locking up the nomination and pushing his two remaining rivals from the race last week. McConnell and others have decided that the best approach is to get behind Trump. But especially in light of House Speaker Paul Ryan's surprise decision to withhold his support, unity is elusive for now.

That could start to change on Thursday, when Ryan, McConnell and other congressional Republicans meet with Trump, who himself has downplayed the meeting and suggested he can win the election unity or no.