Tennessee Republicans head to the polls Thursday to decide the fate of Sen. Lamar Alexander, marking the last chance for tea-party-aligned conservatives to oust an incumbent senator in a primary.  

It will likely be an anticlimactic finish to the primary season in a cycle that featured several potentially vulnerable incumbents, who all swatted away challenges from their right. The second-term senator is favored to prevail against state Rep. Joe Carr, a Republican boosted by conservative radio personalities such as Laura Ingraham and Mark Levin. Carr has little money left, and unlike some of his fellow challengers in other states, outside groups were not generous to him.  

Carr hopes to follow in the footsteps of Dave Brat, whose upset of House Majority Leader Eric Cantor, R-Va., came despite a gaping cash disparity and almost no attention from outside groups or the press.  

But Alexander is an institution in Tennessee, having served two terms as governor and president of the University of Tennessee before joining the Senate in 2003. And he proved to be prepared for such a challenge , raising huge sums of money and locking up support from the major Tennessee political figures early on — ensuring none would challenge him.  

An internal Alexander campaign poll reported by CQ Roll Call last week showed him ahead by nearly 30 points.  

Down ballot, Tennessee is looking at two competitive House Republican primaries. In the 3rd District, Rep. Chuck Fleischmann again faces businessman Weston Wamp, the son of former Rep. Zach Wamp, R-Tenn. Wamp finished third in his primary challenge to Fleischmann in 2012.  

The splashier race is in the 4th, where scandal-plagued Rep. Scott DesJarlais, one of the most vulnerable members, might hold onto his seat.  

Two years ago, DesJarlais was politically toxic. Reports revealed the congressman, a doctor who says he does not support abortion rights, had several affairs with his patients and had pushed his ex-wife to get two abortions before they were married. Since the start of the cycle, he struggled to fundraise, got a strong opponent in state Sen. Jim Tracy and earned a place on Roll Call’s Most Vulnerable House Members list.  

But DesJarlais may survive. The congressman’s hopes hinge on voters focusing on his voting record and forgiving his past.  

All three seats are rated Safe Republican by the Rothenberg Political Report/Roll Call.