Tsongas endorses Warren’s bid for US Senate nomination

“It is not inappropriate that we are here today, with Elizabeth Warren, who again has a chance to make history as the first woman to represent Massachusetts in the US Senate,’’ Tsongas said as she stood in front of a canal and mill buildings that evoked her city’s rich history.

“In the Senate, Elizabeth will fight to level the playing field, so that you have a voice,’’ said Tsongas, the fourth woman to represent the state in Congress.

The announcement was made in the hotly contested Merrimack Valley region, which will be the scene tonight of a debate between the six Democrats vying to challenge Senator Scott Brown, a Republican, who is seeking reelection next year.

Asked about preparing for the debate, Warren replied: “Probably about 30 years. These are the issues I’ve been fighting for my entire adult life.’’

But State Senator Steven A. Baddour, a Methuen Democrat who formerly was a colleague of Brown’s, told WBZ-TV’s Jon Keller: “In order for Elizabeth Warren to win, she’ll need the conservative, moderate Democrats, especially in the Merrimack Valley, to come out and support her. She needs to do a better job at addressing those issues that matter to individuals.’’

The endorsement from Tsongas not only differentiates Warren from Democratic rivals, including City Year founder Alan Khazei and Salem immigration lawyer Marisa DeFranco, but it also provides some emotional push, as well.

Tsongas is the widow of Paul Tsongas of Lowell, who, like Brown, was once the state’s junior senator. She was elected to Congress with aid from EMILY’s List, a group that supports female candidates who favor abortion rights and that has already endorsed Warren.

The endorsement also came a day after a new UMass Lowell/Boston Herald poll showed Warren in a statistical dead heat with Brown and far ahead of the other Democrats.

Warren, a Harvard professor who recently left the Obama administration, would get 36 percent of the vote among Democratic primary voters, while none of her five opponents would get more than 5 percent, according to the poll.

The survey of 1,000 registered voters said Brown would lead Warren by 41 percent to 38 percent, which is within the margin of error of plus or minus 3.8 percentage points.

Noah Bierman can be reached at nbierman@globe.com. Glen Johnson can be reached at johnson@globe.com.