Sen. Ted CruzTed CruzThis week: Shutdown deadline looms over Congress Five things to watch for at Trump-Clinton debate Week ahead: Funding fight dominates Congress MORE's (R-Texas) dad is backing the Tea Party challenger running against Rep. Pete Sessions (R-Texas).
Rafael Cruz, a conservative activist and pastor, endorsed Tea Party activist Katrina Pierson (R) over Sessions at a Monday fundraiser.
Pierson was an early backer of the younger Cruz's come-from-behind Senate primary win. Her fundraiser also featured conservative pundit Michelle Malkin, a sign she might be able to gain traction with the online community of Tea Party activists that often help fund right-wing congressional challenges.
The senator has not weighed in on the race and has not gotten involved in other primaries this election cycle. He's said he'll stay neutral in Senate primaries, though he hasn't explicitly made the same promise about House battles.
Sessions, the chairman of the Rules Committee and former chairman of the National Republican Congressional Committee, is in his ninth term.