The first Massachusetts Senate debate for the seat once held by Secretary of State John Kerry took a contentious tone early on and seldom let up as the candidates sparred over gun control, the attack on the embassy in Libya and more.

Gabriel Gomez, the Republican businessman and former Navy SEAL running for Senate in Massachusetts, wants Attorney General Eric Holder to resign over the seizure of Associated Press phone records. Rep. Ed Markey, the 36-year Democratic veteran of the House of Representatives, does not. Gomez opposes a nationwide ban on "assault weapons"; Markey supports one. Gomez wants a no-fly zone over Syria; Markey doesn't. Gomez doesn't like the medical-device tax; Markey defended the Affordable Care Act. Gomez would consider voting for an anti-abortion-rights Supreme Court justice; Markey wouldn't.

They even agreed on some things. Both want comprehensive immigration reform: "I'll make it a Gang of Nine," Gomez pledged, referring to the bipartisan group of senators who have worked to craft a broad reform bill.

But their clashes onstage Wednesday night weren't so banal. From the moment Markey and Gomez began the first debate of their Massachusetts Senate race to replace Secretary of State John Kerry, the two went at it.

"Congressman Markey, after 37 years in D.C., welcome back to Boston," Gomez said, answering the first question.

"You're gonna hear a lot from Mr. Gomez about how he is a new kind of Republican, but you're going to hear the same old stale Republican ideas," Markey responded.

All that was to be expected of this first meeting, as the campaign has featured its share of negative TV ads. Perceived to be trailing his opponent, Gomez had little to lose, and it showed as he repeatedly attacked Markey's long tenure in Washington and accused the congressman of failing to pass any laws for the last 20 years, lying to the debate audience, and politicizing serious matters for his own benefit.

"You're the first and only political candidate to invoke the Newtown massacre for political gain," Gomez said. "That is beyond disgusting."

A Markey TV ad asserted that "Gomez is against banning high-capacity magazines like the ones used in the Newtown school shooting." Wednesday night, Markey called the idea that he has linked Gomez to Newtown "ludicrous." Gomez, for his part, argued that he would work as a centrist to pass the stalled agreement on expanded background checks, hammered out this year by West Virginia Democratic Sen. Joe Manchin and Pennsylvania Republican Sen. Pat Toomey.

"You're gonna see two different styles here today," Gomez said when Markey raised gun control measures early in the debate. "You're gonna see someone who's gonna try to scare you-I'm gonna speak from the heart. I'm gonna tell you the truth."

Gomez called Markey the "poster boy for term limits" and attacked his legislative record.

"I give you credit for inventing the Internet over 20 years ago," Gomez said, a reference to Markey's boasts about paving the way for Internet and smartphone growth by opposing telecom monopolies. "But the fact is that over the last 20 years you have not authored a single piece of legislation that has been signed into law. Now where I come from in the private sector, the last thing you would do is ask for a raise or a promotion."

Markey called Gomez's assertion flatly untrue, rattling off bills he's passed. WBUR has noted that no Markey-sponsored bill has gone directly to the president for signature, while the American Enterprise Institute's Norman Ornstein told the station that it's wrong to characterize Markey as a do-nothing representative.

"He probably cosponsored those laws," Gomez said, calling Markey's response a "slick, lawyerly, or king of a career-politician" answer.

Gomez called Markey a "hyperpartisan" lawmaker who has "voted with your party 99 percent of the time"; Markey, known as a liberal House member, protested that his career has been dedicated to working with Republicans to pass laws that benefit Massachusetts.

When Markey noted donations to Gomez from national Republican figures, Gomez retorted: "Congressman, if you want to run against, you know, Newt Gingrich or George W. Bush, or even Gerald Ford who was president when you were down there [in Washington, D.C.] for the first time, you should've run against them."

The two sparred over abortion, as Markey hammered Gomez for saying he's open to backing an anti-abortion-rights Supreme Court nominee and that it isn't such a bad idea to require women to wait 24 hours, considering information about their fetuses, before having abortions.

"If they're pro life, and you vote for them, they're going to have the ability to overturn Roe v. Wade, and that's your vote," Markey said. "And you just said to the women of this state that you could support a Supreme Court nominee who could do that."

They also sparred over Benghazi. Both men agree on examining mistakes in that episode, but Gomez pounced on Markey for suggesting that House Republicans had pursued the matter as a means to attack former Secretary of State Hillary Clinton, widely considered a 2016 White House contender. Last month, Markey called Benghazi hearings a "thinly veiled political charade to go after Hillary before the 2016 election" in an interview with The Boston Globe.

"How can you sit here and say that you're more worried about Secretary Clinton's presidential run?" Gomez asked.

"Look, you're the one who's politicizing this," Markey replied, as the two argued over who in fact had politicized it. "You're the one, on the Republican side in the Senate, that's politicizing this issue."

"Congressman, bringing up secretary Clinton's name is politicizing it," Gomez said as Markey argued with him.

And so the debate went: bickering on nearly every issue, with a jab at every turn. As the two argued over whether Gomez would endanger abortion rights if elected-Gomez pledged he would not spend "one minute" trying to change abortion laws-the moderators simply ended the debate and wished viewers a good night.