"This week, in the Utah nominating caucus, I will vote for Senator Ted Cruz," the former Republican presidential nominee wrote on Facebook.
It's clear Kasich, a moderate Republican, is the most Romney-like of the remaining Republican candidates. But it appears Romney is solely focused on thwarting Donald Trump's path to the nomination.
"At this stage, the only way we can reach an open convention is for Senator Cruz to be successful in as many of the remaining nominating elections as possible," Romney said.
Like others throwing their weight behind Cruz, Romney believes a contested convention -- whereby no one candidate has amassed the necessary 1,237 delegates -- is the only way to keep Trump from becoming the Republican nominee.
Though Romney and Senator Lindsay Graham remain intent on keeping Trump from the White House, a new report from Politico's Alex Isenstadt suggests some major Republican donors are ready to throw in the towel after spending millions on anti-Trump advertising -- with little to show for it.
"Some in the anti-Trump movement now concede that the push to defeat him hasn't worked -- and may be backfiring," Isenstadt wrote.