You would expect this from professional politicians whose bread is buttered by their party controlling the presidency. But the significance of several establishment Republican Senators saying they would support Donald Trump if he was the nominee of the party is the recognition that it is politically impossible for them to throw thier support to a Democrat.

The Hill:

Still, even GOP senators who have been at the wrong end of the Republican frontrunner’s barbs say they’ll back him if he becomes their nominee.

“It’s hard to predict because a lot of things happen between now and then but I certainly would support the nominee, no matter who it is,” said Sen. John McCain (Ariz.), the 2008 GOP nominee whose war record and imprisonment in Vietnam was mocked over the summer by Trump.

“I can’t see myself saying a Democratic candidate would be better for the country,” said Sen. Chuck Grassley (R-Iowa), the chairman of the Senate Judiciary Committee.

Republicans for much of the summer have been more worried about whether Trump would back the party’s nominee.

But as the business mogul’s lead in polls has grown higher, Republicans have had to ponder how they’ll handle the possibility of Trump winning the race.

Even the most prudent senators say they would back him in the general election.

“I intend to,” said Sen. Rob Portman (R), who faces a tough re-election in Ohio, a swing state and presidential battleground. “I guess you could come up with some scenario where something crazy could happen but I think the country’s in trouble and I think if we don’t have new leadership and new policies, it’s hard to imagine it getting back on track.”

Sen. Lamar Alexander (R-Tenn.), who ran for president in 1996 and 2000, said, “I have always supported the presidential nominee.”

But he left himself a bit of wiggle room.

“That’s as far as I’m going on presidential politics,” he added.

No members of the Senate have endorsed Trump, though Sen. Jeff Sessions (R-Ala.) was seen at a Trump rally in Alabama wearing one of the candidate’s “make America great” hats and has talked to him about immigration.

Sessions told reporters after meeting Trump on Wednesday that he is not yet making any endorsements in the 2016 presidential primary. They discussed immigration and trade policy.

Senate Majority Leader Mitch McConnell (R-Ky.), who has endorsed Sen. Rand Paul (R-Ky.) for president, declined to get drawn into a discussion about Trump in a CNN interview aired Friday.

He only noted that Trump contributed to his re-election campaign in 2014.

“I appreciate it,” he said.

The question Trump and his supporters may ask is exactly what kind of "support" will these politicians be willing to offer? Will they campaign for him in the fall of 2016? Will they raise money for him? Will they allow him to tap into their state and local networks?  Those are tangible demonstrations of support. Whether they actually offer to do some of those things may make a difference between victory and defeat for Trump.