Vermont Auditor Tom Salmon is launching an exploratory committee to study a challenge to Sen. Bernie Sanders (I-Vt.).

“I do need to take the next step, and that step will be to, beginning tonight, I’m declaring that I’m entering an exploratory phase for U.S. Senate,” the Republican told WCAX-TV in Vermont on Wednesday. He had already announced that he would not seek re-election as state auditor, a statewide elected position he has won three times.

Unseating Sanders is a “daunting task,” Salmon said.

“I think at this point, there are probably three people who think I can win, and the good news is I’m one of them. … The idea here is to make a smart decision before fully declaring myself as a full-time committed candidate for U.S. Senate,” he said.

Salmon was a Democrat until 2009, when he split with the party over fiscal policy. He is also the son of former Vermont Gov. Thomas P. Salmon, who served as the state executive in the 1970s.

Sanders, a self-described socialist who caucuses with Democrats, is in his first term, but he has been a fixture in state politics for decades. Roll Call Politics rates this race Safe Independent.