US Representatives Edward J. Markey and Stephen F. Lynch will launch the first television ads of the Massachusetts Senate race Tuesday, the start of what is expected to be a cascade of commercials as the candidates scramble to introduce themselves to voters before the April 30 primary.

Lynch’s ad, which shows him in jeans and a windbreaker and describes his childhood in public housing in South Boston and his 18 years as an ironworker, is intended to draw a subtle contrast with Markey, who has served in Congress for 36 years. Markey’s campaign would not disclose the contents of his ad.

The dueling spots promise to raise the metabolism of what has so far been a low-profile contest, as both Democrats have focused on wooing and organizing party activists out of the public eye.

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For Lynch, the ad is also something of a gamble. At the last reporting deadline, in December, he had just $800,000 in his campaign account, compared to Markey’s $3.2 million. Lynch is planning to spend at least $200,000 to air the commercial on cable and broadcast stations across the state.

Recent polls have indicated he needs to act quickly if he wants to defeat Markey, who is heavily backed by the national Democratic establishment and liberal activists who exert a large influence in the state’s Democratic primaries.

According to a recent survey by the University of Massachusetts Lowell, Lynch is trailing Markey by a wide double-digit margin. About 42 percent of those surveyed said they had no opinion of Lynch, and 19 percent said they had never even heard of him.

Markey’s decision to launch his own ad campaign five weeks before the primary comes as polls show he is not much better known than Lynch, despite his long tenure in Washington.

About 31 percent of voters in the UMass Lowell survey said they had no opinion of the Malden Democrat, while nearly 19 percent said they had never heard of him. Even among registered voters who said they follow Massachusetts politics closely, about 32 percent said they had no opinion of Markey, and 17 percent said they had never heard of him.

In Lynch’s ad, voters will see him, hands in his jacket pockets, strolling through his childhood home, a brick warren of buildings in the Old Colony housing development. They will also see Lynch walking through a construction site as sparks fly from welding irons and an old photo of the candidate smiling in a graduate’s mortar board and robe.

The goal is to emphasize what Lynch’s campaign believes is the candidate’s greatest asset: his biography as a blue-collar tradesman who worked his way through college and law school before being elected to Congress in 2001.

As the ad closes with Lynch, in a suit, speaking to several people in suits, who listen to him intently, Lynch says: “In Congress, I’ve learned that doing what’s right means knowing when to compromise, and when to stand firm. I believe every working family deserves someone fighting for them.”

Woven into that ad is an implicit criticism of Markey, whom Lynch has been trying to paint as a creature of Washington. Launching his campaign in January, Lynch called Markey “an insulated person” and said, “I can relate to the people I seek to represent in a much better fashion.”

Markey has countered that line by pointing to his own blue-collar roots, as the son of a driver for the Hood milk company.

Both Lynch and Markey must finance their own commercials because both have signed a pact designed to keep outside groups from running ads or sending mailers on their behalf.

The so-called People’s Pledge, which was pioneered by Scott Brown and Elizabeth Warren in last year’s Senate race, aims to hold the candidates accountable for the messages voters receive and to curb the shadowy attacks that characterize modern campaigns.

In the run-up to the general election, on June 30, those outside groups may flood the airwaves with negative attacks because the Republican candidates — state Representative Daniel B. Winslow, former US attorney Michael J. Sullivan, and former Navy SEAL Gabriel E. Gomez — have declined to sign the pledge.