Republican Sen. Ted Cruz said he will do whatever he can to defeat Democratic presidential nominee Hillary Clinton, including campaigning for Donald Trump and helping with debate preparation.

The Texas senator has been criticized for refusing to endorse Trump during the Republican Party convention in July, before finally offering his support on Friday.

“If I were being political, I would have endorsed Donald Trump back in Cleveland at the convention,” Cruz told radio host Hugh Hewitt on Tuesday. 

[Trump Wins Ted Cruz’s Vote With Supreme Court List]

Rather, he said, he withheld his endorsement until the Trump campaign released a list of 21 potential judges to replace the late Supreme Court Justice Antonin Scalia. 

When Cruz sat down with vice presidential nominee Mike Pence three weeks ago, he told the Indiana governor that the Supreme Court was the major issue that would make him come onboard. Once the list was finalized and released, Cruz said he was pleased with the candidates.  

“It’s a terrific list, and the commitment on Friday they made that they would only nominate from that list, to me, was a big deal, and that was enough to move me over to a yes,” Cruz said. 

Cruz, who won the Princeton Debate Panel’s Team of the Year award in 1992 with his partner Dave Panton and went on to debate during his time at Harvard Law School, added that he would be “happy to help” Trump with debate preparation. 

Aside from stopping Clinton, retaining a Republican majority in the Senate is another focus for Cruz.

The entire conversation can be heard here.