Mitt Romney will give an anti-Trump speech tomorrow:

“Mitt doesn’t believe Donald Trump is the right person to lead the party,” the Republican said. “There are a number of mainstream Republicans falling in line with Trump, and he wants to speak up before more people go that route.”

While making the case against Trump, Romney is unlikely to endorse one of his opponents [bold mine-DL], the source said.

Romney has mostly refrained from inserting himself in the 2016 campaign, and he has been reluctant to endorse anyone, so it’s not surprising that he won’t be offering an endorsement this week. The odd thing about Romney’s intervention is that it doesn’t seem likely to help any of Trump’s rivals and just reminds Trump supporters of what they hate about the party leadership. My guess is that most Trump supporters see Romney as the embodiment of everything they don’t like about the GOP, and a Romney attack on Trump could very well be a boon for the front-runner. It’s possible that Romney might discourage a few fence-sitting politicians from lending their support to Trump, but that’s not going to make any of the remaining candidates any more competitive.

Former nominees don’t usually attack candidates in their own party, and it is even rarer for losing nominees to do so. Losing nominees normally recognize that they’ve had their chance at leading the party and failed in the attempt, and because of that they tend not to try influencing later contests. The Republicans that would take Romney’s advice are already against Trump, and Romney is more likely to drive away the ones that might be persuaded to oppose him. Though the contests are different in many ways, Romney’s speech reminds me a bit of Tony Blair’s desperate and ineffective effort to derail Corbyn’s leadership bid last year. In both cases, you have a discredited former leader trying to tell a party that has lost confidence in him what they should do, and in both cases the former leader merely demonstrates how out of touch he is with his own party. I suspect Romney will be no more successful in rallying anti-Trump Republicans than Blair was in preventing Corbyn’s election, and he will fail for some of the same reasons.