Armed with a sizeable war chest and several big-name endorsements, Sonoma County Supervisor Mike McGuire made it official Monday by announcing he is running for the state Legislature.

The 34-year-old Healdsburg resident, who was seen as a virtual shoo-in for re-election to the county Board of Supervisors next year, is forsaking relative job security for the chance at a much larger prize, albeit one that pays considerably less than what he earns now.

McGuire said Monday that it's "never been about money for me. It's about delivering results for the constituents I work for."

McGuire enters the race for the 2nd District Senate seat as the presumptive favorite. Santa Rosa Democrat Noreen Evans is not running for re-election next year, ostensibly to return full-time to her private law practice.

When he kicked off his re-election campaign for supervisor in August, McGuire said he already had raised $160,000, money that can be transferred to his Senate campaign under state rules governing such moves.

McGuire announced Monday that his campaign is being endorsed by North Coast Congressmen Mike Thompson and Jared Huffman, as well as by retired Congresswoman Lynn Woolsey.

"I think Mike is entering very strongly and likely will be the presumed front-runner now that he's announced," said Stephen Gale, chairman of the Sonoma County Democratic Party.

Freshman Santa Rosa City Councilwoman Erin Carlstrom also has announced a run for the Senate seat, as have Chris Lehman, a 36-year-old Arcata resident and longtime state Senate staffer, and Eric Lucan, 32, who was elected to the Novato City Council in 2011.

Since the highest voter turnout historically has been in Sonoma and Marin counties, candidates from those areas would appear to have an advantage going into the contest. But Gale said McGuire and Carlstrom risk splitting the vote. And there's always the possibility of more candidates entering the fray, further diluting the vote.

McGuire, a Healdsburg High and Sonoma State graduate and former marketing director at KFTY-TV50, dominated his 2010 race for the north county supervisor's seat, and he was in a strong position to do the same in 2014.

Fellow Supervisor Efren Carrillo had also been considering a bid for the Legislature, but decided not to run after his arrest in July on suspicion of prowling and burglary. Asked whether he would have entered the race if Carrillo was running, McGuire said, "I can't answer that."

McGuire also declined to say whether he was approached by anyone to run for the Senate seat.

Should he prevail, McGuire would take a sizeable pay cut. State senators are paid an annual salary of $95,291, not including a per diem and other benefits. As a county supervisor, McGuire earned $134,322 in 2012, plus an additional $76,500 in benefits.

The 2nd District presents a logistical challenge for any successful candidate. Under redistricting, the territory includes all of Marin, Mendocino, Lake, Humboldt, Trinity and Del Norte counties. In Sonoma County, it takes in Santa Rosa, Sebastopol, Windsor, Healdsburg, Geyserville and Cloverdale.

Voter registration in the district is heavily Democratic. The majority of its more than 1 million residents are centered in the more urbanized south, including Sonoma and Marin counties.

McGuire said his focus will be on job growth, schools, the coastline and revitalizing state parks.

"My goal is to always be the hardest working person in the room," he said.