WASHINGTON — Rep. Pat Tiberi’s decision Tuesday to pass on running for the U.S. Senate is a sign that Republicans are growing increasingly worried that President Donald Trump’s ragged first few months in office may cripple GOP candidates next year.

Although many analysts had privately predicted that Tiberi would not yield his relatively safe House seat in Genoa Township for a risky bid against Democratic Sen. Sherrod Brown, they said a number of Republicans see Trump’s growing unpopularity as a major obstacle next year.

“It’s hard to give up seniority in the House for an uncertain future,” said Jennifer Duffy, senior editor for the nonpartisan Cook Political Report in Washington. “More importantly, a lot of House members who are thinking of moving up are looking at what the political landscape may be in 2018, and they don’t like what they are seeing.”

Dennis Eckart, a former Democratic congressman from Cleveland and a Brown ally, said, “Republicans are not recruiting well for 2018, and Donald Trump giving away the secrets of Fort Knox to the Russians doesn’t help. You wake up every morning and wonder, ‘What am I going to have to explain away today?’”

Tiberi’s announcement all but guarantees that Republicans will nominate state Treasurer Josh Mandel, who lost to Brown in 2012. Mandel is trying to emulate Trump’s anti-immigrant, anti-Muslim-extremist populist appeal from last year’s election, which appeared to resonate with blue-collar workers in the upper Midwest.

But with Trump's approval ratings now low, one Ohio Republican said Mandel “can’t run as a mini-Trump. Sherrod Brown is already a populist. There’s going to be a need for another formula.”

Tiberi said he could have won a party primary next year because he does not “have the baggage of losing to the current incumbent already," a none-too-subtle jab at Mandel.

“I believe I could have been the best candidate to win a seat in November of 2018 on our side,” Tiberi said. “But it became clear to me over the last several weeks that it was going to be something that I couldn’t do with 100 percent effort (considering) my job and responsibilities.”

Tiberi cited his role as a member of the House Ways and Means Committee, the tax-writing panel in the House. That means Tiberi has a chance to fashion a major package to overhaul the nation’s tax code.

“Tax reform — we have been talking about that for years and now we’re in a position to do it, and I didn’t want to back off of that to run around the state,” said Tiberi.

Tiberi, 54, has $6.3 million in his campaign treasury account, compared with $4.9 million for Brown and $2.44 million for Mandel. But to run for Senate, he would have been forced to spend millions to increase his name identification across the state.

jtorry@dispatch.com

@jacktorry1