Ohio Gov. John Kasich warned Monday that nominating Donald Trump or Ted Cruz will cost Republicans control of the New York state Senate, adding to the political damage the party fears could result from November’s elections.
Analysts have already said the U.S. Senate and even the U.S. House could slip from Republican control if Mr. Trump or Mr. Cruz is the nominee, but Mr. Kasich said the losses could go even deeper, reversing a six-year surge the party had been enjoying at the state level.
“I think we have a good chance of having a united Republican Party with nominees who are going to get destroyed in the fall election,” Mr. Kasich said as he campaigned ahead of the April 19 New York Republican primary. “I will tell you the majority in the New York state Senate will not be a majority with the other two guys being the nominee of the party.”
Unable to win the nomination outright, Mr. Kasich is hoping Republicans go to their convention in July worried less about their internal fight and more concerned with who’s their best bet to lead the party into November.
He has been making the case that he’s the Republicans’ best chance not only to face off against either Democratic front-runner Hillary Clinton or Sen. Bernard Sanders, but also to give them a credible chance at coattails further down the ballot.
Polling suggests that Mr. Trump and Mr. Cruz would struggle against either Democrat, while Mr. Kasich runs ahead of Mrs. Clinton and is competitive with Mr. Sanders.
Republican Party strategists fear that a blowout at the top will trickle down to other races, costing Republicans seats they otherwise would win. That includes not just federal races but all the way down to state offices, analysts said.
“There are many state legislative chambers that could flip if there’s a lopsided presidential result,” said Kyle Kondik, managing editor of the political newsletter “Larry J. Sabato’s Crystal Ball.”
The Crystal Ball recently shifted six U.S. Senate races more toward Democrats’ favor in response to the Republican primary situation.
New York, meanwhile, doesn’t have a competitive U.S. Senate race, but its state Senate will be on the ballot. The chamber is split with 31 Republicans and 31 Democrats, but the GOP retains effective control thanks to alliances.
“Across the state, what will a Trump candidacy mean for retaining control of the New York state Senate?” said Gerald Benjamin, a political scientist at the State University of New York at New Paltz.
A recent Quinnipiac University Poll on New York showed Mrs. Clinton and Mr. Sanders beating Mr. Trump and Mr. Cruz by between 20 and 28 points, while Mr. Kasich trailed Mrs. Clinton by just 5 points and trailed Mr. Sanders by 10 points.
In nearby Pennsylvania, Quinnipiac found Mr. Kasich beating Mrs. Clinton by 16 points and beating Mr. Sanders by 6 points. Mr. Trump, meanwhile, lost to Mr. Sanders by 8 points and Mrs. Clinton by 3 points, and Mr. Cruz lost to Mr. Sanders by 8 points and tied Mrs. Clinton.
Both Mr. Cruz and Mr. Trump insist they’ll be competitive in a general election and dispute each other’s chances.
“The polling shows over and over again that, unlike Donald Trump, that with me as the nominee, we beat Hillary Clinton,” Mr. Cruz said Monday at a rally in California.
Mr. Trump, for his part, says he’ll draw millions of new voters to the polls, pointing to the record turnout for the GOP primaries so far. He also said he’ll eat into Democrats’ base by winning over blue-collar workers and political independents.
He’ll get an early test of his coattails next week when, in addition to the Democratic and Republican primaries, there are several elections for New York state assembly seats. One of those is to fill the seat of Republican Dean Skelos, the former Senate majority leader who stepped down last year amid federal corruption charges.
“Democrats have a very strong candidate, so the issue is what will the turnout, Democrat and Republican turnout, be, and how will that translate in the Senate election?” Mr. Benjamin said.
Mr. Kondik said many of the races where GOP Senate incumbents are looking to get re-elected in November are in states where the presidential election will also be decided, and highlighted Arizona, Missouri and North Carolina as Senate races to watch.
“All three Republican incumbents are favored, but they all have somewhat soft numbers at home and could be vulnerable under the right set of circumstances,” he said. “If Democrats end up having a very big year in the Senate, those could end up being surprises on election night.”
Meanwhile, Democrats, looking to hold onto governorships in states such as Missouri and West Virginia, could see a boost with Mr. Cruz or Mr. Trump at the top of the ticket, Mr. Kondik said.