Former Texas Gov. Rick Perry attempted to encourage U.S. Rep. Michael McCaul to challenge fellow Republican Sen. Ted Cruz’s re-election bid in 2018, the Texas Tribune reported on Monday. Two GOP sources familiar with correspondence between Perry and McCaul said that the encouragement of a primary challenge to Cruz came as grassroots conservatives grew uneasy with the current senator’s refusal to endorse Donald Trump at the Republican National Convention. (Cruz later caved, endorsing Trump in late September.) Neither Perry’s nor McCaul’s respective camps would deny the correspondence, and the six-term congressman has spent some time criticizing Cruz over the past few months. “I think he’s spent a lot of time since day one running for president,” McCaul said of Cruz during an interview last week with the Tribune. “I think we deserve somebody in the Senate who is going to be representing the interests of the state of Texas.” However, McCaul has not publicly stated whether he intends to run for Cruz’s seat.