House Speaker Paul D. Ryan (R-Wis.) sent an urgent fundraising appeal Thursday evening that warned: “If we fail to protect our majority in Congress, we could be handing President Hillary Clinton a blank check.”

Whether or not it was intentional, the phrase “blank check” has a political echo — one that suggests a deep fear by congressional Republicans that a sinking presidential candidate could take their majorities in the House and Senate with him, and that they are getting ready to desert him.

It goes back 20 years, to an infamous chapter in internecine Republican politics. In the weeks before the 1996 presidential election, as it became clearer and clearer that GOP nominee Bob Dole would not defeat incumbent president Bill Clinton, Republican operatives began urging their struggling congressional candidates to begin making the argument: “Let’s not give Clinton a blank check.”

In late October of that year, the National Republican Congressional Committee spent $4 million on television ads in 50 congressional districts where races were close. The final shot was of a blank check hovering over the Capitol dome. It was signed: “American taxpayer.”

For Dole, the implication that even his own party had given up on him was a devastating blow.

The Washington Post’s Philip Rucker explains how unusual it is that Republican presidential nominee Donald Trump is withholding his endorsements of House Speaker Paul D. Ryan (R-Wis.) and Sen. John McCain (R-Ariz.) in their primary races. (Bastien Inzaurralde/The Washington Post)

One of Dole’s top strategists that year was Paul Manafort, who is now Trump’s campaign chairman. Dole’s personal assistant was Michael Glassner, who has worked for Trump’s campaign for more than a year. A number of other Dole staffers now work for Trump.

Ryan used the words “blank check” at least three times Thursday, as Trump sat below Clinton in the polls and continued to deal with the aftermath of controversies of his own making. This week, Trump refused to endorse Ryan in the Wisconsin Republican primary and praised Ryan’s underdog opponent, Paul Nehlen. It was a snub that angered many Republican leaders.

[Paul Ryan says Trump’s campaign is ‘distressing’ but stands by endorsement]

“I like Paul, but these are horrible times for our country,” Trump said in an interview with The Washington Post on Tuesday. “We need very strong leadership. We need very, very strong leadership. And I’m just not quite there yet. I’m not quite there yet.”

Trump’s campaign and Ryan’s office have yet to respond to requests for comment. Katie Martin, a spokeswoman for the National Republican Congressional Committee, said the historical comparison is unfair.

“There is no news here, nothing to read into, no secret message about the upcoming elections,” Martin said in an email. “The possibility of giving Hillary Clinton a Congress led by Speaker Nancy Pelosi would be an unmitigated disaster for the American people — as it was 8 years ago with President Obama.”

In the 1996 election, Republicans lost nine seats but managed to hold the House, the first time they had done so in consecutive elections in more than 60 years. This year, Republicans have a bigger cushion — their strongest House majority since 1930.

Republican presidential nominee Donald Trump found himself in the middle of multiple controversies, all in the space of a few days. Here's a breakdown. (Peter Stevenson/The Washington Post)

However, they also have a standard-bearer who is far more toxic. In 1996, Dole was viewed positively by most voters, even as he lost. Trump, on the other hand, has the most unfavorable ratings of any candidate ever to lead a major party ticket since the advent of polling.

Ryan’s first use of the term “blank check” came during an interview with WTAQ radio in Green Bay, Wis., where Trump will hold a rally Friday night. Host Jerry Bader pressed Ryan on his support for Trump, despite the nominee’s ongoing controversial utterances. Ryan said he would remain behind Trump while continuing to speak out when he disagrees with him.

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When asked whether there would ever be a point at which he would abandon Trump, Ryan said of his endorsement: “None of these things are ever blank checks.”

It was the standout line of the interview and appeared in numerous headlines. Hours later, the words popped up twice in Ryan’s fundraising appeal that was sent to email addresses collected during Wisconsin Gov. Scott Walker’s failed presidential campaign.

The email reads: “96 days — that’s all the time we have left before Americans head to the polls on Election Day, and much more is at stake than the presidency. If we fail to protect our majority in Congress, we could be handing President Hillary Clinton a blank check.”

Clinton in the White House and Nancy Pelosi as the House speaker “would truly be devastating for our great nation,” the email continues, and it urges donations of $25 to $100.

The email is signed “Speaker Paul Ryan” and includes this P.S.: “We cannot afford to give Hillary Clinton a blank check if she’s elected president. We need a strong, conservative majority in Congress as our last line of defense.”

Mike DeBonis contributed to this report.