Senator Bernie Sanders is airing the first television ad of his campaign, a biographical spot that describes his up-by-the-bootstraps childhood in Brooklyn, incorporates imagery of the late Dr. Martin Luther King Jr. and paints him as “an honest leader.”

The spot is part of a $2 million purchase of airtime in Iowa and New Hampshire, according to Mr. Sanders’s campaign.

The ad is an introduction to the Vermont senator for many voters, even those in the neighboring state of New Hampshire. And it comes after Mr. Sanders made a major departure from his standard stump speech during last weekend’s Iowa Democratic Party Jefferson-Jackson Dinner and made a string of veiled attacks on his main rival for the nomination, Hillary Rodham Clinton. In turn, she and her allies have recently made claims of sexism — some oblique, some overt — that Mr. Sanders’ team has had difficulty countering,

While the ad never mentions Mrs. Clinton, the reference to Mr. Sanders as “honest” is a veiled contrast with the former secretary of state, who has seen the number of voters who view her as “honest and trustworthy” sink amid a summer of questions about her use of a private email server while she was at the State Department.

“The son of a Polish immigrant who grew up in a Brooklyn tenement. He went to public schools, then college where the work of his life began,” the narrator intones. “Fighting injustice and inequality. Speaking truth to power. He moved to Vermont, won election and praise — as one of America’s best mayors.”

The spot goes on to note his opposition to the authorization of using military force in Iraq in 2002, an issue that dogged Mrs. Clinton in her 2008 presidential race against then-Senator Barack Obama.

“Now, he’s taking on Wall Street and a corrupt political system,” the spot says, before hitting on Democratic touchstones like his support of clean energy, a living wage and equal pay. It also stresses Mr. Sanders’ support for tuition-free public colleges.

“Bernie Sanders,” says the narrator. “Husband. Father. Grandfather. An honest leader — building a movement with you, to give us a future to believe in.”

The only time Mr. Sanders himself appears in the ad is in footage from one of his rallies, in which he says, “People are sick and tired of establishment politics and they want real change.”

