The former state natural resources commissioner has now outraised Sen. Mark Begich (D-Alaska) the past two quarters, by a total of about $700,000.

Begich raised $1.05 million during the first three months of the year and has $2.8 million cash on hand, the same amount he held at the end of the year.

( POLITICO’s On the Ground series)

Sullivan’s main opponent for the GOP nomination, Lt. Gov. Mead Treadwell, has not reported his figure. But he has struggled to raise money, and his campaign manager and media consultant left the campaign last month. A third Republican candidate, Joe Miller, raised only $30,000 during the fourth quarter of last year.

“Our growing momentum highlights the increased frustration with the fact that Mark Begich is a rubberstamp for President Obama’s liberal agenda, supporting his policies 97 percent of the time,” Sullivan said in a statement, which added that he received more than 1,000 small-dollar donations.