Former Maine Gov. John Baldacci (D) has decided against running for retiring Sen. Olympia Snowes (R-Maine) seat, a source close to Baldacci said Wednesday.

Baldaccis decision removes a major hurdle for another former governor — Angus KingAngus Stanley KingFor .2 billion, taxpayers should get more than Congress’s trial balloons Overnight Health Care — Sponsored by PCMA — Trump hits federally funded clinics with new abortion restrictions Dem senators ask drug companies to list prices in ads MORE — who is running for Senate as an independent and could have lost votes to a big-name Democratic candidate.

Baldacci, who represented Maine in the House for four terms before becoming governor, said hundreds of volunteers had encouraged him to run and had gathered more than the 2,000 required signatures to get him on the ballot.

But it’s time for me to come home to Maine, not to re-up for a potential six more years down in Washington, said Baldacci, who has worked for the Defense Department for the past year. This is the right decision for me and my family.

Snowe’s decision in February not to seek another term created an unexpected opening for Democrats to flip a Republican-held seat. A handful of candidates had already announced plans to challenge Snowe, a popular centrist Republican.

But with Snowe out of the picture, Democrats upped their recruitment efforts, appealing to Maine Reps. Michael Michaud (D) and Chellie Pingree (D) to consider running. Both eventually opted out.

The dynamics of the race changed dramatically when King entered the race in March, leaving both parties nervous about how their candidates would fare with an independent in the race. Early polling showed King leading a three-way race for the seat.

King has refused to say which party he would caucus with if elected — a decision that could determine the balance of power in a divided Senate. But Republicans continue to speculate that King has struck a deal with Senate Democrats.

This only further confirms that national Democrats know that Harry ReidHarry Mason ReidMcConnell not yet ready to change rules for Trump nominees The Hill's Morning Report — Sponsored by CVS Health — Trump’s love-hate relationship with the Senate Trump to press GOP on changing Senate rules MORE has Angus King’s vote in his back pocket, said National Republican Senatorial Committee spokesman Brian Walsh.

Democrats were put in a particularly difficult situation when King entered the race: Polling showed King would peel off mostly Democratic votes and could deliver the seat to Republicans, making it a safer bet for Democrats to back King and hope he would caucus with them. But they realized that publicly backing an independent over Democrats in the race would be seen as an affront to those candidates.

Baldacci’s exit from the field of potential candidates all but ensures that Senate Democrats will cast their lot with King, who pursued fiscally conservative policies as governor but leaned more toward Democratic positions on social issues and the environment.

But the Democratic field will not be empty. A handful of lesser-known Democrats are planning a run for the seat, including state Sen. Cynthia Dill, who was already in the race before Snowe announced her retirement, but considered running instead for the House seat that Pingree would have vacated had she made a run for Snowe’s Seante seat.

We are delivering in excess of 2,000 certified signatures to the [Maine] secretary of state’s office tomorrow, Dill told The Hill in an email.

With Baldacci out as a possible foil for King, the GOP has an even tougher path to hold on to the seat. But Senate Republicans have opted to take their chances rather than prop up King and hope he caucuses with them. At least three Republican candidates are expected to file for the primary ballot.

Candidates have until Thursday to turn in signatures to run for Snowe’s seat.