JUNEAU — A national tea party group that heavily backed Republican Joe Miller’s campaign four years ago has not decided whether to endorse anyone in this year’s Republican U.S. Senate primary.

Sal Russo, co-founder and chief strategist for the Tea Party Express, told The Associated Press on Monday that the philosophical contrast between the candidates is “not as dramatic” as it was in 2010.

“They’re all pretty much running on a conservative platform,” he said.

Miller was the group’s choice in the 2010 GOP primary because it saw a clear contrast between him and the incumbent, Sen. Lisa Murkowski, he said.

The group saw Murkowski as part of the problem in Washington and endorsed Miller, who upset her in the primary. Miller wound up losing the contentious general election to Murkowski, who mounted a write-in campaign to keep her job.

Miller is running again this year and is one of three prominent Republicans in the race. The others are with Lt. Gov. Mead Treadwell and former state Natural Resources Commissioner Dan Sullivan.

They are seeking to replace Democrat Mark Begich, a first-term senator up for re-election. Republicans see the seat as key to their efforts to win back control of the Senate.

Russo said his group finds this year’s top GOP contenders to be philosophically similar.

In evaluating candidates, the Tea Party Express looks at several criteria, including how committed they would be to reducing the size and cost of government, their ability to put together viable campaigns, a demonstration of grassroots support and examples that show they would be willing to make difficult decisions, even if they’re unpopular, he said.

Of the major Republican contenders, “I think we’re convinced that all three of them have that ability and willingness to stand up and make tough choices and get the country back on track,” Russo said.

Russo said his group is carefully monitoring the race. “But we haven’t gotten to the point of whether there’s one candidate we think is so much better that we should get engaged at this point. We may yet,” he said.

“We really need to find a candidate that will be effective in beating Begich,” Russo said.

He said defeating Begich is one of his group’s highest priorities this year, and he expects the Tea Party Express to be involved in the race at some point.