Representative Chris Pappas, a four-term congressman, defeated progressive challenger Karishma Manzur in the New Hampshire Democratic Senate primary on Tuesday, according to The Associated Press.

Mr. Pappas, 46, who represents New Hampshire’s First District, prevailed over Ms. Manzur, a medical scientist and member of the Southern New Hampshire Democratic Socialists of America, who sought to harness anti-establishment sentiment and shifting views on Israel that have disrupted Democratic primaries nationwide.

His victory sets up a general election contest against former Senator John E. Sununu, who easily secured the Republican nomination. The seat is being vacated by retiring Senator Jeanne Shaheen, a Democrat who endorsed Mr. Pappas. A recent University of New Hampshire poll showed Mr. Pappas trailing narrowly behind Mr. Sununu, with both parties preparing for a high-stakes battle backed by millions in outside spending.

Mr. Pappas, a moderate Democrat from Manchester, has raised over $15 million, far outpacing Ms. Manzur, who collected less than $500,000. He received endorsements from former Vice President Kamala Harris and active campaigning from Senators Elizabeth Warren and Mark Kelly. If elected, he would be the first openly gay male senator.