North Carolina Secretary of State Elaine Marshall (D) filed paperwork on Tuesday to open a Senate campaign committee, taking her first official step toward running for the seat held by Sen. Richard Burr (R).

Thomas Mills, a consultant for Marshall, told the Charlotte Observer that a formal campaign announcement will come later.

Democrats have been actively trying to recruit a top-tier challenger to Burr, whom polls have shown to be vulnerable in 2010, but they have thus far found little success.

Attorney Kenneth Lewis is the only other Democrat in the race, but several other potential candidates are mulling bids, including Rep. Bob Etheridge, former Lt. Gov. Dennis Wicker and former state Sen. Cal Cunningham.

This is not Marshall’s first Senate bid. She ran in the 2002 open-seat race when Sen. Jesse Helms (R) retired, but she finished a disappointing third in the Democratic primary. She was elected secretary of state in 1996.