Senate Minority Leader Harry Reid jumped on both Tuesday, first attacking Trump for his criticism of Sen. John McCain, R-Ariz., then pivoting to a larger target: the growing GOP presidential field and the entire Republican Party.
Reid, D-Nev., noted that while Trump's GOP White House rivals were nearly unanimous in denouncing Trump's suggestion that McCain is not really a war hero, they were more tentative in responding to his criticisms of Mexican immigrants as "criminals" and "rapists."
"There is an ugly truth behind that silence, and it is this: When it comes to immigration policy, there is no meaningful difference between the Republican Party and Donald Trump," Reid asserted.
Republicans want to insert considerable distinctions between themselves and Trump. Responding to him only emboldens him, several in the GOP acknowledged Tuesday.
For his part, McCain told fellow Senate Republicans in their private weekly lunch on Tuesday that he's finished commenting on Trump's provocations.
"John stood up and basically said, 'I'm not going to respond to Donald Trump,'" recalled Sen. Dan Coats, R-Ind. The caucus, Coats and other Republicans said, gave McCain a round of applause.
Reid, meanwhile, went on to name former Florida Gov. Jeb Bush, Texas Sen. Ted Cruz, New Jersey Gov. Chris Christie and Wisconsin Gov. Scott Walker, noting that all oppose a pathway to citizenship for immigrants in this country illegally.
"So while the rest of the Republican presidential hopefuls may not engage in the same repugnant rhetoric, make no mistake about it - they are all on the same page with Donald Trump," Reid said. "I ask each Republican running for president: Name one difference between your immigration policy and Trump's immigration policy. Given recent history, all I expect is a deafening silence."
Reid's comments followed similar criticism from other Democrats, including presidential candidate Hillary Rodham Clinton.
Clinton, in Arkansas this past weekend, said of Trump's comments: "It's shameful, and so is the fact that it took so long for his fellow Republican candidates to start standing up to him. The sad truth is if you look at many of their policies, it can be hard to tell the difference."
Trump has defended his comments on immigrants and on McCain, who spent five years as a prisoner of war in Vietnam. Trump said he likes people who weren't captured.
Immigration is a perennially tricky issue for Republicans, which may help explain why some of the presidential candidates have been cautious in their response to Trump on that issue. Indeed Cruz has been outspoken in praising Trump on immigration.
That prompted Sen. Claire McCaskill, D-Mo., to snipe over Twitter: "There's something unseemly about Cruz following Trump around like a lost puppy, hoping to get his leftovers when he finally flames out."