In the letter, Lugar Political Director David Willkie encouraged Indiana Republicans not to follow the lead of the Delaware, Nevada and Colorado GOP, arguing that if they had taken "the Reagan 'big tent' approach [in 2010], we would have already repealed Obamacare.


"I encourage all Republican leaders to rally around the Dick Lugar flag now; you have been led down a wrong path and it's time to come home," Willkie wrote, referencing the entry of Rep. Joe DonnellyJoseph (Joe) Simon DonnellyLobbying world Trump nominees meet fiercest opposition from Warren, Sanders, Gillibrand GOP frets over nightmare scenario for Senate primaries MORE (D-Ind.) into the Senate race Monday.

Democrats see an opening in 2012 should Mourdock, who has won the backing of several Tea Party groups, defeat Lugar in a GOP primary. The Democratic Senatorial Campaign Committee labeled it a prime pickup opportunity with Donnelly in the race.  

Still, Mourdock said Tuesday that he's confident he can beat the Democrat should the two face off in next year's general election, comparing Donnelly's profile to that of former Rep. Brad Ellsworth (D-Ind.) who lost a Senate race to Republican Dan CoatsDaniel (Dan) Ray CoatsTrump has named more ex-lobbyists to Cabinet in 3 years than Obama, Bush did in full terms: report Hillicon Valley: FCC approves Nexstar-Tribune merger | Top Democrat seeks answers on security of biometric data | 2020 Democrats take on Chinese IP theft | How Google, Facebook probes are testing century-old antitrust laws Congress should defy Dan Coats' last request on phone surveillance MORE last fall.

"I'm sure Donnelly will try to run as a Blue Dog, pro-life, pro-gun Democrat," Mourdock said. "That's the same thing Brad Ellsworth did last time and I'm not sure what he's doing now because he was soundly defeated."