Senior Senate Republicans are calling on Sen. Ted Cruz to rebuild his strained relationships with his colleagues and apologize to Majority Leader Mitch McConnell before the party establishment considers consolidating behind his presidential bid.

Cruz has increasingly called for Republicans to unify behind his candidacy in order to take down front-runner Donald Trump. But in interviews Tuesday with CNN, it’s clear Cruz’s fellow GOP senators are not willing to do that, at least not yet.

Republican senators said that Cruz must return to Capitol Hill and make the case directly to his colleagues to help ease long-festering tensions. And a large number of Republicans said the fence-mending starts with this: Apologizing to McConnell for calling him a liar last year on the floor of the Senate.

That message was personally delivered by fellow Texan and McConnell’s chief deputy, Sen. John Cornyn, who spoke with Cruz by phone after the candidate won their home state’s primary earlier this month.

“I actually made that suggestion to him when I talked to him last,” Cornyn said when asked if he thought Cruz should apologize for his McConnell remarks.