BUSTED: These 10 GOP senators said Ukraine quid pro quo was a red line before Bolton bombshell

The Washington Post's Philip Bump has tracked down statements from ten different Republican senators who in the past indicated that impeachment charges against President Donald Trump would be far more serious if it could be proven there was a quid-pro-quo agreement that involved exchanging the release of foreign aid to Ukraine for the investigation of former Vice President Joe Biden.

All of the statements flagged by Bump came before this week's bombshell revelation that former national security adviser John Bolton's upcoming book will reportedly say the president directly linked Ukraine aid to the Biden investigation.

This possibility of a linkage between the aid and the Biden probe was dismissed as unlikely by these senators last fall -- but they did indicate that it would change things if such a linkage were proven.

"So just a few days ago the Democrats were breathlessly on TV saying, ‘You’re going to see an illegal quid pro quo. It’s going to prove that,'” Sen. Ted Cruz (R-TX) said during an interview on Fox News. "Well, you look at the transcript -- there’s no illegal quid pro quo in that transcript."

"It would be troubling if any president did a quid pro quo with tax dollars," said Sen. Kevin Cramer (R-ND). "But so far we don’t have evidence that’s happened."

“There was no quid pro quo,” said Sen. Chuck Grassley (R-IA). "You’d have to have that if there was going to be anything wrong."

"If you could show me that Trump actually was engaging in a quid pro quo, outside the phone call, that would be very disturbing," Sen. Lindsey Graham (R-SC) said.

Read all of the quotes from Republicans at this link.