Indiana state Senator Mike Delph (R) hinted at a primary challenge to Sen. Richard Lugar (R-Ind.) in an email to supporters Friday.
The conservative state lawmaker, who has been mentioned by some Tea Party activists in the state as an early favorite to take on Lugar, said he was "deeply moved" by the encouragement he has received in recent weeks.
"Senator Lugar is my Senator and I have supported him in the past, but have become increasingly concerned with his actions on my behalf and on behalf of Indiana within the last few years," Delph wrote.
Lugar has quickly become a top Tea Party target in 2012, with activists in Indiana and nationwide vowing to find a candidate to oust the longtime Senator in a Republican primary.
While Delph said he has "neither ruled in nor ruled out" a run, he certainly sounded like a candidate in the message, going after Lugar's support of the DREAM Act.
Delph demanded an apology from Lugar for his spokesman Mark Helmke's suggestion "that those of us who object to the DREAM Act, a bill that would grant blanket amnesty to thousands of illegal immigrants, are 'un-American.' It is my hope that Sen. Lugar apologizes for the words of his staff and clearly lets them know that differences of viewpoint are precisely American."
Delph also noted his strong reelection showing in his state Senate district, saying it's a large part of the reason he's considering a statewide run.
"I was just re-elected 59%-41% in a Senate district President Obama won 56%-44%," he wrote.
Another rumored contender in a GOP primary against Lugar is Indiana's state Treasurer Richard Mourdock.
For his part, Lugar appears unconcerned by the prospect of a Tea Party-backed primary challenge. The senator has spent the lame duck session defying his party on a range of high profile issues including the DREAM Act and the START Treaty.
Lugar also refused to sign onto an earmark ban, a signature issue among Tea Party activists.
In a recent interview with The Hill, Lugar said he didn't think his party has moved too far to the right for him and said he fully intends to run for reelection in two years.
"These are just areas where I’ve had stances for a long time," Lugar said. "I didn’t adopt them to be contrary. I think what’s occurring is, the Democrats are trying to get passage for things in the last stages of their majority, so a number of these issues have arisen because of that. I have no other explanation."
-J. Taylor Rushing contributed to this article