Democrat Rep. Ed Markey is the winner of the Massachusetts special election to fill the Senate seat vacated when John Kerry became secretary of state, defeating businessmen and former Navy SEAL Gabriel Gomez.

Markey was leading 55 percent to 45 percent with 99 percent of precincts reporting, according to The Associated Press.

Markey told his cheering supporters he will "seek consensus wherever possible. Like you, I am tired of gridlock. But I will never compromise on our principles."

"I am going to the U.S. Senate to build a bold and bright future filled with optimism and opportunity for every family in the state of Massachusetts and across our great country," Markey said in his victory speech.

Gomez also thanked his supporters, but noted his uphill battle.

"In the military you learn one thing, I guess, that not every fight is a fair fight," Gomez said in his concession speech. "Sometimes you face overpowering force. We were massively overspent. We went up against literally the whole national Democratic party and its allies and the machine. But in the face of this great adversity, we could not have fought a better fight."

It was a highly anticipated, but tighter than expected, victory for Markey, 66, with one of the last polls in the race from the Boston Globe last week showing him leading Gomez by 13 points.

It preserves a state of normalcy in Massachusetts, with two Democratic senators representing the blue state, as it was before Sen. Ted Kennedy passed away in 2009 and Republican Scott Brown won that special election. Brown was defeated last year by Democrat Elizabeth Warren.

Democrats have a significant voter registration advantage over Republicans in Massachusetts and longtime political observer and Tufts professor of political science, Jeffrey Berry says that explains Markey's victory more than anything else.

"The overwhelming reason Gabe Gomez lost is because he's a Republican and for every Republican there are more than three Democrats and the obstacles facing Gomez were daunting," Berry said.

Markey's win shows he may not have needed the extra firepower he brought into the race, despite being a 37-year veteran of the House at a time Congress couldn't be disliked more. President Obama, first lady Michelle Obama, former President Bill Clinton and Vice President Joe Biden all came to campaign for him, not taking anything for granted despite the Democratic landscape.

But the closeness of the race may be good news for Gomez' political future, Berry said.

It could also mean hand-wringing and second-guessing for the GOP. Outside groups didn't pour money into the race, despite Gomez being the type of candidate national Republicans have said they want to support.

He was a Harvard-educated, former Navy SEAL, successful businessman and second-generation Colombian immigrant, but it wasn't enough for outside groups to spend more. The Gomez team was even unafraid to say they felt that they were being left in the lurch, openly urging Republicans to spend more in the last days of the race.

"This is the world's longest psychotherapy session," Brad Todd, a top Gomez strategist said in an interview with ABC News last week, referring to the GOP's post-election soul-searching. "We've gotten awful comfortable on the couch. It's time to get up and get in the game."

The National Republican Senatorial Committee did send staff to help out on the ground, as well as hold fundraisers for Gomez. NRSC chairman Jerry Moran, R-Kan., sent an e mail to donors Monday saying they had spent nearly $1 million on the race.

Of course, aside from his intriguing personal story, Gomez was far from the perfect candidate. His temperament on the stump was called into question when he called his opponent "pond scum" for running an ad that pictured Gomez as well as Osama bin Laden. The Markey ad hit Gomez for his association with a group that accused Obama of politicizing bin Laden's death.

Among the lines of attack that stymied Gomez was whether he took advantage of a tax loophole improperly, although not illegally. Markey also consistently hit Gomez, noting his policy stances on abortion and gun control.

Gomez has said he is "personally pro-life," but wouldn't attempt to change abortion law, calling Roe vs. Wade "settled law," in an interview with the Boston Globe. He accepts exemptions like rape, incest or danger to the life of the mother, but none of that seemed to matter in the face of ads and stump speeches that painted Gomez as an extremist.

Gomez consistently said he would work across the aisle and with Obama, even writing an open letter to him "welcoming" him to Massachusetts when he campaigned for his opponent. He said voters needed new leadership after 37 years of Markey in the House, consistently stressing that Markey lived in Maryland, not Massachusetts, but the line of attack never really caught on.

Voter turnout was reportedly low Tuesday, as was interest in the race throughout the campaign. It could be because of election fatigue for Bay State residents, who have endured the 2010 special Senate election, the 2010 gubernatorial election, a 2012 Senate election and the 2012 presidential election.

Residents won't escape it anytime soon. In 2014, there will be another Senate election for Markey and whatever Republican decides to run against him for the complete term. There will also be an open governor's race as Democrat Gov. Deval Patrick has said he will not run again.