Pingree said it was a difficult decision and that she's grateful for the support she's received from across Maine and the country. In the end, she concluded that she can best serve the people of Maine by running for re-election in the U.S. House, she said in a statement.
"Although the prospect of running for and possibly serving in the United States Senate was very exciting, I believe I will best serve the people of Maine by running for re-election to the House," she said. "There is much at stake in this election, and in the end I had to put the best interests of the state and the country ahead of my own."
Snowe, a moderate Republican, announced last week that she wouldn't seek a fourth term, citing frustrations over partisan politics and gridlock in the Senate.
Her decision set off a scramble by potential candidates since Republicans and Democrats have only until March 15 to submit 2,000 signatures to get on the June primary ballot.
If Pingree had run for Senate, she would've faced her longtime friend, popular former Gov. Angus King, who announced he's running as an independent, in addition to a Republican challenger. Another Democrat, former two-term Gov. John Baldacci, is weighing whether to run. Four other Democrats are already in the race, but some said they'd consider stepping aside if Pingree chose to run.
On the GOP side, previously announced candidate Scott D'Amboise now faces up to four GOP competitors, including former state Sen. Rick Bennett. They could be joined by Secretary of State Charles Summers, Attorney General William Schneider and state Treasurer Bruce Poliquin.