A Heated Debate Along a Growing Republican Divide

So that’s what a civil war looks like on a debate stage. For two hours in Detroit, Donald J. Trump and the three men who want to stop him from getting the Republican nomination battled over his pronouncements on foreign policy, his business record and his past views on overseas wars.

Senator Marco Rubio of Florida and Donald J. Trump at the Republican debate on Thursday in Detroit.Credit

It was not a strong debate for Mr. Trump, who was on the defensive throughout. And yet, that has never mattered before. On the one hand, Mr. Trump’s affirmative case for himself began with a veiled joke about his genitalia, and never really went far from there. 

On the other hand, Senator Ted Cruz of Texas and Senator Marco Rubio of Florida spent almost all of their time making a case against Mr. Trump rather than herald their candidacies. The Republican Party fractured onstage, making the bitter Democratic primary fight of 2008 between Hillary Clinton and Barack Obama seem tame. 

It was hard to keep track of all the invective hurled at Mr. Trump, and it’s why the speech that Mitt Romney made against him hours earlier might have been more effective. 

Mr. Cruz, Mr. Rubio and the three moderators offered a jumble of attacks and criticisms against Mr. Trump, creating a lot of noise. The issue that seemed likeliest to stick was the continuing lawsuit over Trump University, which, in a surreal moment for a major candidate, Mr. Trump called a “minor civil case.” 

Gov. John R. Kasich of Ohio declined to join in the mudslinging, and insisted that he had a positive vision for the country. But he also repeatedly declined to directly answer what was asked of him, shifting to a topic he preferred. 

While Mr. Trump’s rivals landed some blows against him, they’ve chosen to take him on most strongly when he is a 10-state winner. Perhaps the most important moment of the debate was at the end: After calling Mr. Trump uninformed, dangerous and ill-suited for the presidency, both Mr. Cruz and Mr. Rubio said they would support him as the party’s nominee. For Mr. Rubio, who is struggling not to lose his home state of Florida on March 15, it could be a dangerous statement.

In the meantime, four more states will vote on Saturday, with a primary in Louisiana and caucuses in Maine, Kansas and Kentucky, states where Mr. Cruz could perform well.