Former Massachusetts governor Mitt Romney is finally getting off the sidelines to endorse Sen. Marco Rubio, in a final effort to defeat Donald Trump after the billionaire took early states in New Hampshire and South Carolina by storm.

According to the Huffington Post’s Scott Conroy, Romney had been waiting for Jeb Bush to exit the race before endorsing Rubio, citing “respect” for the former Florida Governor.

But with the establishment field clear, the former failed Republican nominee plans to embrace Rubio. According to the report, Romney may rally with Rubio ahead of the Nevada caucuses on Tuesday. Romney won Nevada easily in both the 2008 and the 2012 presidential caucuses.