LAWRENCE, Mass. (AP) — Democrat Edward Markey and Republican Gabriel Gomez promised to highlight differences in both substance and style in the first of three debates between the U.S. Senate candidates over the final weeks of a special election campaign that has yet to fully engage the Massachusetts electorate.

Markey, a 36-year veteran of the U.S. House, and Gomez, a financial executive and former Navy SEAL, were scheduled to square off Wednesday evening in a debate sponsored by WBZ-TV and The Boston Globe.

The candidates said they were looking forward to the debates that were shaping up as pivotal for both men but especially Gomez, who has touted his political newcomer status but remains an unknown quantity to many Massachusetts voters.

"I'm a plain-spoken, direct kind of guy," Gomez said Tuesday after touring Polartec, a Lawrence textile company.

"I'm going to speak from the heart and I'm going to convey the following message: This election is about the future, not the past. It's about having new ideas and fresh ideas as opposed to old and stale ideas," he said.

Despite his long tenure in Congress, Markey was little known before the Senate campaign outside his House district in Boston's northern and western suburbs, and has tried to deflect criticism that he's an out-of-touch Washington insider.

"I think it's important for us to talk about the big issues and to ensure that the voters out there know what the differences are between me and Gabriel Gomez," Markey said of the upcoming debate.

Markey invoked Democratic royalty during a campaign appearance Monday with Caroline Kennedy, saying Gomez does not represent "mainstream Massachusetts values," as the Kennedy family did.

Gomez, meanwhile, has lately tried to distance himself from the national Republican party, saying he planned on being a "pain in the butt" to GOP Senate leaders.

But Democrats moved quickly to undermine Gomez's claim of being a new style of Republican. A 30-second TV ad launched by the Markey campaign on the eve of the first debate argues that on abortion, Social Security and guns, Gomez echoes his party's line.

For Gomez, the perceived underdog, the challenge in the debate is to sound qualified enough to handle the job of senator, according to Jeffrey Berry, a Tufts University political science professor.

"He needs to create an image of someone who is knowledgeable about the issues. He's had trouble getting beyond platitudes when asked direct questions," Berry said. "He needs to project something more than just that he's a good guy with a great biography."

Markey, by contrast, "needs to project some dynamism. He has to counter the image of someone who is past his prime and been in Washington far too long," Berry said. Markey also needs to put the race into national context to make sure voters cast their ballots based on policy, not personality, Berry said.

The campaign for the Senate seat formerly held by U.S. Secretary of State John Kerry was overshadowed for weeks by the deadly April 15 Boston Marathon bombings. The race has so far failed to generate anything close to the level of public interest as a 2010 special election to fill the seat of the late Sen. Edward Kennedy that was won by Republican Scott Brown, or last year's race in which Democrat Elizabeth Warren unseated Brown.

Wednesday's debate is scheduled to end just moments before the Boston Bruins and Pittsburgh Penguins face off across town in Game 3 of the NHL Eastern Conference finals, raising further questions as to just how focused some voters might be on the debate.

Markey and Gomez were also scheduled to meet in western Massachusetts June 11 and again in Boston on June 18.

The special election is June 25.

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Associated Press writer Steve LeBlanc in Boston contributed to this report.