The Democratic favorite is a 37-year veteran of Washington, a loyal and established party soldier who's seeking a promotion to the Senate after a career in the House.
The Republican challenger is a newcomer to national politics, a Harvard-educated former Navy SEAL and second-generation Colombian immigrant who's running against the political establishment.
Gabriel Gomez would seem to be precisely the kind of candidate the post-2012 Republican Party would be looking for, in the kind of race they'd be looking for him in. On paper, it's a dream matchup for Republicans, in the state that -- while heavily Democratic -- vaulted Scott Brown from obscurity to the Senate during President Obama's first term.
Yet with barely a week left in the Massachusetts Senate special election to fill the seat John Kerry vacated when he became secretary of state, national groups on the Republican side are notably silent, even as Democrats pour in outside support for Rep. Ed Markey.
Gomez has already been outspent by nearly $4 million. Republican insiders say Gomez is likely to be swamped, spending-wise, six- or seven-to-one in the final stretch of the race, barring a late cash infusion.
Gomez allies are beginning to sound off about the lack of support they're drawing from national Republican donors, including the outside groups controlled by the likes of the Koch brothers and Karl Rove.
Brad Todd, a top Gomez strategist, said national Republicans appear to have grown too timid after the 2012 electoral wipeout. If they can't support a Latino entrepreneur and military veteran against a career politician, he asked, what are they waiting for?
"This is the world's longest psychotherapy session," Todd said in an interview, 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 evidence here is that Democrats are scared to lose, and Republicans are scared to win," he added.
Said Lenny Alcivar, another top campaign official and someone who has worked extensively on behalf of Latino Republicans: "Gabriel Gomez is exactly the kind of Republican that so many of us in the Republican Party have been looking for. Grab an oar and get in the boat."
Republican National Committee Chairman Reince Priebus said he believes Gomez offers a template for a brighter GOP future. He said he hasn't given up hope on national donors embracing the Gomez-Markey race as the opportunity it is, saying that it will be a "a late-breaking race."
"I wish we could have 100 Gabriel Gomezes out there in our party," Priebus told ABC News. "I hope for every ounce of help that Gabriel can get in this race. I'd like it to come. I hope it will come."
On the ground in Massachusetts, the clash of biographies hasn't quite defined a campaign that's turned on smaller issues of long-ago tax breaks and tax votes, and one candidate comparing the other to "pond scum."
Still, the race is giving both parties a chance to test-drive messaging and mobilization for next year's midterm congressional elections and beyond. It's also revealing anxieties inside both parties about a still-turbulent political landscape.
On the Democratic side, the clear sense is that the party won't allow itself to witness a rerun of Brown's stunning 2010 victory.
"The takeaway is: We like to win elections. We don't take anything for granted," said Rep. Debbie Wasserman Schultz, chair of the Democratic National Committee, who, herself, has made one trip to Massachusetts and has another on tap before the election. "The campaign and the candidate who ignores and lacks respect for the voters loses elections."
Markey has been eager to make the stakes national, casting Gomez as a vote for Mitch McConnell and the GOP agenda. The old Obama campaign apparatus is mobilizing on Markey's behalf with manpower and money in a race Wasserman Schultz said allows Democrats to run the kind of effort they did in 2012 "in microcosm."
Underscoring the stakes, President Obama, first lady Michelle Obama, former President Bill Clinton and Vice President Joe Biden all have made recent appearances for their longtime ally.
But the fact that such efforts appear necessary in deep-blue Massachusetts has some Democrats more worried than ever about the 2014 landscape. Democrats will be defending 21 of the 35 Senate seats on the ballot next year, with Democratic-held seats in states including Montana, South Dakota, West Virginia, Arkansas and Louisiana posing particular challenges.
"I think Markey will win," said Jim Kessler, a senior vice president at the centrist Democratic group Third Way and a longtime Senate aide. "But this is a race in which you'd expect it to be easier. You would still bring the big guns in to be safe, but you wouldn't really feel like you needed them."
Kessler said he fears that voter anger at Congress will be felt primarily by Democrats next year. Democratic control of the White House and the Senate could leave the party playing a tough brand of defense in states without anywhere near the Democratic edge they enjoy in the Bay State.
"There was hope that after Obama got elected, more would get done in Washington," Kessler said. "I'm not sure if the anti-incumbency [sentiment] is a wave or a breeze."
Biden gave voice to Democrats' midterm concerns at a Markey fundraiser last week. He referenced the difficulties Democrats are likely to face in an election where the president won't be on the ballot.
"There's a big difference in this race: Barack Obama's not at the head of the ticket," the vice president said. "And that means those legions of African-Americans and Latinos are not automatically going to come out. No one has energized them like Barack Obama. But he's not on the ticket. So don't take this one for granted."
Priebus sees the big-name Democrats campaigning for Markey as a sign of Democrats' worry. The RNC is putting some of its post-election data and research projects to a test drive in the state.
The RNC chairman said he hopes the race sends a message that Republicans can compete -- and win -- in all corners of the country.
"It's pretty clear from looking at all the Democrats going into Massachusetts, they're pretty concerned," Priebus said. "Being active and competitive everywhere helps us in every state in the country."
It's that sentiment, plus Gomez's biography, that has some Republicans thinking the race could be winnable, if only Gomez could compete financially with Markey.
"He's in a very similar situation that Scott Brown was in," said Ron Bonjean, a veteran GOP strategist who is not working for Gomez. "He's a good candidate for Republicans. What there hasn't been is enough buzz to drive a Republican donor base to flood the state with cash. They're nervous about what happened in 2012, where a lot of Republican donors and Super PACs spent money on candidates that lost. They're still smarting from it."
Gomez is far from a perfect candidate. His temperament on the stump was called into question with his comparison of Markey to "pond scum" for running an ad that pictured Gomez as well as Osama bin Laden. (The ad hit Gomez for his association with a group that attacked President Obama for politicizing bin Laden's death.)
Gomez, moreover, has cast himself as a moderate independent voice, with a vow to be a "pain in the butt" to national Republicans. Back in January, when Gov. Deval Patrick was set to fill Kerry's old seat temporarily, Gomez made a private plea to Patrick that included a pledge to "support the positions that President Obama has taken" on gun control and immigration reform.
One Republican strategist who's been tracking the race said that outside donors have been watching it closely for signs that it's winnable. But they haven't yet seen polling to suggest that Gomez is in realistic striking distance in the heavily Democratic state. Much of the publicly released polling has had the margin in the low double-digits.
Plus, the strategist said, there's little appetite to throw money around carelessly, particularly in light of the flawed 2012 polling that suggested a big night for Republicans.
Yet, to the view of many in the party, the chance of a Republican Senate pickup is too tempting to ignore. There won't be too many opportunities like this, surely not in states as blue as Massachusetts, they argue.
"Regret is a hell of a lot more expensive than risk," said Todd, the Gomez campaign strategist. "And if Gabriel Gomez loses, there's going to a whole lot of regret."