A national tea party group that heavily backed Republican Joe Miller's campaign four years ago hasn't decided whether to endorse anyone in this year's GOP Senate primary.

Sal Russo, co-founder and chief strategist for the Tea Party Express, tells The Associated Press Monday that his group became involved in the 2010 primary because there was a clear contrast between the two Republican candidates, Sen. Lisa Murkowski and Miller.

The group endorsed Miller, who won the primary but lost the general election. Murkowski won that with a write-in campaign.

Miller is running again this year, with Lt. Gov. Mead Treadwell and former state Natural Resources Commissioner Dan Sullivan the other prominent Republican candidates.

Russo says the philosophical contrast between the candidates is not as dramatic as it was in 2010.