By his own admission, U.S. Rep. Chris Murphy should have been in Washington D.C. Thursday voting on an extension of unemployment benefits and the payroll tax holiday, instead he was at the state Capitol in Hartford receiving the endorsement of the Working Families Party—thanks to Republicans in Congress who are holding up the vote on the extensions.

The endorsement is for his U.S. Senate campaign and it comes with the promise of volunteers to go door knocking, make phone calls, and help get out the vote.

Murphy, who is being challenged for the Democratic nomination by former Secretary of the State Susan Bysiewicz, and state Rep. William Tong of Stamford, said he’s not responding to the policy proposals put out by his opponents and is just asking voters to take a look at his record in Congress. 

The frontrunner in the race, according to all polling data to date, Murphy said his strategy is to focus on both the primary and the general election with an eye toward building “the best ground campaign this state has ever seen.”

He said if former World Wrestling Entertainment CEO Linda McMahon ends up being his opponent in the general election, he’s going to need a good ground game because he won’t be able to outspend her. McMahon spent $50 million in her 2010 campaign against now U.S. Sen. Richard Blumenthal.

Murphy noted that the margin of victory in his 2006 defeat of Republican Nancy Johnson was the Working Families Party line. He said the support of the Working Families Party also made a big difference in the 2010 gubernatorial contest.

The Working Families Party doesn’t usually make endorsements this early in a contested race, however, they felt comfortable making one for both Murphy and House Speaker Chris Donovan, who is running for Murphy’s seat in the 5th congressional district. The endorsement means their name will appear twice on the general election ballot if they make it through their Democratic primaries.

Jon Green, executive director of the Working Families Party, said in addition to the forum they held for the U.S. Senate candidates, they also reviewed questionnaires, and held several meetings to debate their choices before voting Monday to endorse both Murphy and Donovan.

“We recognize that both are going to be hotly contested races and we wanted to give ourselves enough time to come up with a game plan,” Green said.

The endorsement comes with “great political power” and “moral authority” to speak for working families in the state of Connecticut, Murphy said.

“We are in a fight for the future existence of the middle class right now,” he said. “We are going to make a decision in Washington D.C. over the next five to 10 years over whether we want a middle class in this country or whether we’re just going to recede into a world with 95 percent have-nots and 5 percent haves.”

“There are things we can do to make working families strong again,” Murphy told a small group gathered for the announcement on the south side of the Capitol.