New rifts emerged Friday in the already shaky relationship between Republican leaders and presumptive presidential nominee Donald Trump, heightening concerns that the party is headed into a long period of civil war that imperils its chances in the November elections.

A day after House Speaker Paul D. Ryan of Wisconsin took the unusual step of refusing to support Trump, a steady list of other Republican notables joined in the opposition, including former Florida governor Jeb Bush, Sen. Lindsey Graham of South Carolina and 2012 presidential nominee Mitt Romney.

Trump, in turn, attacked Ryan and others for refusing to back him, even as he agreed to meet with Ryan next week to air out their differences.

And at the White House, President Obama waded into the opposition’s turmoil for the first time since Trump effectively clinched the nomination, listing concerns about the mogul that he said Republican voters must seriously consider.

For Trump and Republican elites, it amounted to another awkward chapter in their uneasy alliance, not the celebratory moment many had hoped would arrive when the Republican contest was settled.

Trump’s outsider candidacy and outsize persona – and his extreme positions on issues including immigration and Islam – have alarmed broad swaths of the Republican establishment that fear the party is headed for a wipeout in the fall if Trump is not contained or kept at arm’s length. For his part, Trump argues that his brash campaign triumphed over the rest of the Republican field fair and square, and he has suggested he is unlikely to budge on his positions to please Republican leaders.

Amid the upheaval, there was at least one encouraging sign for Republicans hoping that the party comes together: Trump and Ryan agreed to sit down face-to-face.

“Having both said we need to unify the party, Speaker Ryan has invited Donald Trump to meet with members of the House Republican leadership in Washington on Thursday morning to begin a discussion about the kind of Republican principles and ideas that can win the support of the American people this November,” Ryan’s political office said in a statement.

But Trump was tepid in his own statement on the planned gathering, saying he had agreed to talk to Ryan “before we go our separate ways.”

Bush posted a message on Facebook on Friday afternoon saying that he would not support Trump or Clinton.

“He has not displayed a respect for the Constitution,” Bush said of Trump. “And, he is not a consistent conservative.”

Graham, another former presidential candidate, had backed Bush and later Sen. Ted Cruz of Texas in hopes of stopping Trump. He released a statement Friday saying that he “absolutely will not support Hillary Clinton” but “cannot in good conscience support Donald Trump.”

“I do not believe he is a reliable Republican conservative nor has he displayed the judgment and temperament to serve as Commander in Chief,” the statement said.

According to the Washington Examiner, Romney, who plans to skip the Republican National Convention this summer, said at an awards gala Thursday evening, “I don’t intend on supporting either of the major-party candidates.”

Some Republicans have gone further, saying they plan to back Clinton over Trump or are at least considering it. Fielding questions from reporters Friday, Obama said Republicans will have to do soul-searching when it comes to the presumptive Republican nominee.

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