The National Review, a conservative standard-bearer, has endorsed Indiana state Treasurer Richard Mourdock (R) over Sen. Dick Lugar (R-Ind.), making it the latest leading conservative to align behind the Tea Party favorite.

"Lugar evinces a political philosophy so subtle that in unfavorable light it scarcely seems to exist at all," the paper's editorial board writes, pointing to his votes in favor of the auto bailout, President Obama's Supreme Court nominees and the DREAM Act, which would allow some undocumented immigrants brought to the United States at a young age a path to citizenship.

The paper also takes a dig at Lugar's ongoing residency issues — he hasn't lived in Indiana for more than three decades and had to fend off a legal challenge as to whether he'd be able to vote in the state at all. "Lugar has become a carpetbagger in his own state," they write.

Polls show a tight race between Lugar and Mourdock, who also has the support of the fiscally conservative Club for Growth and FreedomWorks, the National Rifle Association and socially conservative groups including the Eagle Forum and Indiana Right to Life.

Read the full endorsement here.