Representative Michael E. Capuano raised almost twice as much as his challenger, Ayanna Pressley, in the second quarter of the year, extending his strong fund-raising advantage as he tries to fend off a vigorous challenge from the Boston city councilor.

Capuano’s campaign said Thursday that the veteran congressman from Somerville pulled in $680,000 in the quarter, compared with $370,000 that Pressley’s campaign reported collecting during the period. Capuano’s campaign said it now has $1.4 million cash on hand and expressed confidence that that sum would far exceed the amount in Pressley’s campaign account.

Pressley’s camp refused to release how much is in her campaign account. Such figures do not have to be released until July 15, when they must be reported to the Federal Election Commission. But at the end of the last fund-raising period, on March 31, Pressley had about $260,000 in her account.

“Mike is grateful for the grass-roots support he has received from volunteers and donors in every part of the district, and will continue to fight for progressive values, taking on Donald Trump at every turn,’’ said Audrey Coulter, press secretary for the Capuano campaign.

“Mike isn’t taking anything for granted in this campaign, and will continue to work hard for all communities every day,’’ she said.

Capuano also dominated in fund-raising in the first quarter of the year, when he raised more than $500,000 to Pressley’s $364,000. Pressley’s camp said, however, that it sees signs of growth in her overall fund-raising base. Aides said Pressley collected 2,400 contributions in the second quarter of the year, compared with 1,500 in the first quarter.

“This is a grass-roots, people-powered campaign and I am extremely grateful for the outpouring of support,’’ Pressley said in a statement.

Pressley also boasted that, unlike Capuano, she is refusing to accept money from corporate political action committees. The average contribution to her campaign was $125, and 1,900 of the donations came from donors in Massachusetts, Pressley’s campaign said.

“Ayanna is focused on championing the issues that matter most in our communities,’’ Sarah Groh, Pressley’s campaign manager, said in a statement. “Voters in the Seventh want bold leadership, not politicians beholden to pharmaceutical companies and financial institutions while the Trump administration erodes access to health care and dismantles the Consumer Financial Protection Bureau.’’

The fund-raising period included four days following Alexandria Ocasio-Cortez’s upset victory over Representative Joe Crowley in New York, which gave Pressley a burst of positive national attention.

In the 36 hours after that election, Pressley’s camp said she collected nearly $18,000 and approximately three times the number of contributions collected in the same period the previous week.

But Capuano’s campaign said Ocasio-Cortez’s stunning win also awakened his base. His aides said he collected $150,000 during the four days after Crowley lost.

Michael Levenson can be reached at michael.levenson@globe.com.