Less than 24 hours after Democrat Edward J. Markey was elected to the Senate, the race to replace him in the House of Representatives was already in full swing.
A bevy of ambitious local officials unfurled their campaigns Wednesday for the mostly suburban Fifth Congressional District seat that runs from Revere to Lexington to Framingham to Holliston.
Many of those campaigns were effectively under way, however, in the months after Markey began his US Senate campaign.
State Representative Carl M. Sciortino of Medford, state Senators Will Brownsberger of Belmont, Katherine Clark of Melrose, Karen Spilka of Ashland, and Middlesex County Sheriff Peter J. Koutoujian of Waltham, all Democrats, filed federal paperwork to run for the Fifth Congressional District seat before Markey’s victory Tuesday night.
But now that Markey has won, the candidates’ tentative campaigns have become full-fledged efforts looking toward an expected fall primary election.
All except Koutoujian told the Globe Wednesday that they are definitely running. Koutoujian said in a statement that he looks forward to making an announcement about the open seat in the days ahead.
Facing primary voters in the heavily Democratic district, candidates tried to both emphasize their party bona fides and what differentiated them from other contenders.
Sciortino, backed by about 25 sign-wielding supporters, announced his bid Wednesday in a press conference in which he ticked off issues he said he had led on in his State House tenure, from abortion rights to workers’ rights to “equality for women and LGBT people,” referring to lesbian, gay, bisexual, and transgender people.
In his speech, he positioned himself to the left of his opponents.
“I am proud to have a consistent progressive record of leadership,” the five-term legislator said. “No other candidate in this race can say that.”
Spilka, in her fifth term, said she plans a campaign kickoff July 1. In an interview, she said that “the thing that sets me apart from the other candidates is my background in conflict resolution.”
She cited her time as a social worker, labor lawyer, and arbitrator and spoke about her “ability to bring competing interests to common ground.”
Brownsberger, in his first full term, said his “commitment to addressing the long-term challenges the country faces” is what differentiates him from the field. He said the economy, environmental issues, and poverty were three of those challenges.
Clark, in her second term, said she is running to work on issues “around families and being a voice for them and the middle class.”
“I am going to stand up to the extremists who are challenging access for women to health care that they deserve and they need,” she added.
The field is far from set, with other potential candidates eying the seat.
One political figure who could enter the race as a front-runner is former state senator Warren Tolman, who was the 1998 Democratic nominee for lieutenant governor. The Watertown resident is said to be giving serious consideration to a bid and is expected to decide in the next few days.
The date of the election will not be scheduled until Markey officially resigns to become a US senator, said Brian S. McNiff, a spokesman for the Massachusetts secretary of state. Markey’s aides said that that will probably occur after the July Fourth holiday weekend.
After that resignation takes effect, state election law calls for Governor Deval Patrick to schedule a special election for a date from 145 to 160 days later, which probably means that the special election will be held in December with an earlier primary contest.
Markey, who has represented the area for almost 37 years, was asked Wednesday whether he intends to endorse a candidate to replace him.
“I don’t have any plans on that subject,” he said.
Political observers do not see an immediate front-runner among the declared candidates, who face what could be a challenging political environment as they try to introduce themselves to an exhausted electorate, worn out by one political contest after another.
“Coming on the heels of our presidential and senate elections last year and a Senate election that just ended,” said Peter N. Ubertaccio, a political science professor at Stonehill College, “there’s only so much political oxygen in the tank.
“The candidates are going to have to fight really hard to gain some name recognition,” he added.
US Representative Michael E. Capuano, who won a contested Democratic primary for an open US House seat against nine opponents in 1998, said no candidate’s geographic base of support would, alone, be enough for victory.
He advised the candidates for the Fifth Congressional District to work hard to introduce themselves to people outside the municipalities that elected them. But he added that strategy is only part of the equation for victory.
“Bottom line,” Capuano said, “there’s only one way to do it, and that’s old-fashioned shoe leather.”Frank Phillips of the Globe staff contributed to this report.
Joshua Miller can be reached at email@example.com. Follow him on Twitter @jm_bos.