While Ensign's decision to position himself alongside some of the most conservative members of the Senate in voting against the tax cut compromise may boost his conservative credentials, his pursuit of earmarks may provide an opening for Heller to attack in a potential primary. At the same time, Heller could be criticized for not pursuing money for the state.
The tax cuts also proved to be a divisive issue in Utah. Sen. Orrin Hatch (R-Utah) may see a primary challenge of his own from Rep. Jason Chaffetz (R-UT), and the two parted ways on the issue, with Hatch supporting the compromise and Chaffetz opposing the measure.
Moving East, two senators also viewed as potentially vulnerable in 2012 made some key moves that will likely help their chances in 2012. Connecticut Sen. Joe Lieberman (I) helped shepherd a repeal of "Don't Ask Don't Tell" through the Senate, even after the measure's prospects once appeared faint. Lieberman, who has angered voters on the left in the past, has likely upped his credibility with some Democrats following the victory of the DADT repeal -- which would no doubt help him in a bid, whether he decides to run as a Democrat or independent.
Massachusetts Sen. Scott Brown's (R) eventual support of the DADT repeal gave the measure timely momentum and also gave Brown a boost. Pair that with his support of the New START treaty that also passed the Senate after much debate, and Brown has proven himself to be someone who, at times, the Obama administration can work with.
Brown, along with Ensign, is widely considered to be a top target for Democrats in 2012, and his support for DADT and New START reveals a keen awareness of the balance a statewide Republican candidate must strike in Massachusetts.