Voted against cutting funding for ACORN
In September 2009, following the lead of their Senate colleagues, the House of Representatives voted overwhelmingly to cut off funds to ACORN. the vote was 345-75. All of the 75 were Democrats, and included Niki Tsongas. 
Reception Honoring Martha Coakley
On Jan. 12, 2010 a reception honoring Martha Coakley was held at the Sonoma Restaurant, 223 Pennsylvania Ave, Washington D.C. Among those present were Senator John Kerry and Representatives, Ed Markey, Richard Neal, William Delahunt, John Tierney, Stephen Lynch, Barney Frank, John Olver, Jim McGovern, Michael Capuano and Niki Tsongas.
Hosts of the reception donated $10,000 and included Nick Allard, Thomas Hale Boggs Jr., the Boston Scientific Political Action Committee, Chuck Brain, Susan Brophy, Mary Beth Cahill, Steve Champlin, Licy Do Canto, Gerald S. J. Cassidy, David Castagnetti, Steve Elmendorf, Candy Ergen, Cahrlie Ergen, Shannon Finley, Larry Harris, Tom Hogan, Carol Kenner, Stephanie Markiewicz, Andy Miller, Heather Podesta, Tony Podesta, Robert Raben, Linda Singer and Bill Titelman.
Co-hosts of the reception donated $5,000 and included Marty Bienenstock, Sheryl Cohen, Chad Dale, Joe Eyer, Jamie Gorelick, Robin Leeds, Fred Liowther, Bernie Nash, Frank Purcell of the CRNA (Nurse Anesthetists) Political Action Committee and Melissa Schulman.
Tsongas received $500 in lobbying funds from Planned Parenthood in 2008.
Tsongas has been supported by EMILY's List during her campaigning.
Supported by Council for a Livable World
The Council for a Livable World, founded in 1962 by long-time socialist activist and alleged Soviet agent, Leo Szilard, is a non-profit advocacy organization that seeks to "reduce the danger of nuclear weapons and increase national security", primarily through supporting progressive, congressional candidates who support their policies. The Council supported Niki Tsongas in her successful 2008 House of Representatives run as candidate for Massachusetts. He has also been previously supported by the Council.
Anti-Fracking legislation endorser
On March 14, 2013, Rep. Jared Polis (D-CO) and Rep. Matt Cartwright (D-PA) have introduced the Bringing Reductions to Energy’s Airborne Toxic Health Effect (BREATHE) Act, and the Focused Reduction of Effluence and Stormwater runoff through Hydraulic Environmental Regulation (FRESHER) Act, in order to ensure that the hydraulic fracking industry follows the same rules that other industries do in preserving our natural resources. This legislation is focused on ensuring the safety and the health of the communities where the hydraulic fracturing, or fracking, process is already taking place.
The BREATHE Act would ensure that we close the oil and gas industry’s loophole to the Clean Air Act’s aggregation provision, in addition to adding hydrogen sulfide—a chemical associated with nausea, vomiting, headaches, and irritation of the eyes, nose, and throat—to the Clean Air Act’s federal list of hazardous air pollutants.
The BREATHE Act has the following original co-sponsors including: Reps. Rush Holt, Jr., Raul Grijalva, John Sarbanes, James Moran, Michael Quigley, Earl Blumenauer, Gerry Connolly,Zoe Lofgren, Michael Honda, Paul Tonko, Barbara Lee, David Price, Carolyn Maloney, Michael Capuano, Mark Pocan, Jim McDermott, Eleanor Holmes Norton, Alcee Hastings, Keith Ellison, Niki Tsongas, William Keating, Adam Smith, Jim Langevin, Chellie Pingree, Judy Chu, Louise Slaughter, Jerrold Nadler, Grace Meng, Jan Schakowsky, Nita Lowey, Jared Huffman, Gary Peters and Alan Lowenthal.
The following organizations have endorsed this legislation and are actively working to garner support within Congress and throughout the country: Physicians for Social Responsibility, Natural Resources Defense Council, Earthjustice, Alliance of Nurses for Healthy Environments, Sierra Club, Earthworks, Breast Cancer Action, Clean Water Action, Environment America, Greenpeace, Nature Abounds, Oil Change International, Citizens for a Healthy Community, Citizens for Huerfano County, Clean Water Action Colorado, Erie Rising, Grassroots Energy Activist Network, Holy Terror Farm, San Luis Valley Ecosystem Council, SOS Foundation, Western Colorado Congress of Mesa County, Western Slope Conservation Center and Wilderness Workshop.
JStreet endorsed her again in 2016.
- Tsongas sits on the Armed Services and Natural Resources Committees. She is a champion of the two-state solution, having traveled to Israel and witnessed firsthand the importance of resolving the Israeli-Palestinian conflict.
ARA endorsement, 2014
Condemning Criticism of Islam legislation
On December 17, 2015, Rep. Don Beyer, Jr. introduced legislation condemning "violence, bigotry, and hateful rhetoric towards Muslims in the United States." The legislation is based on unsourced claims that there is a "rise of hateful and anti-Muslim speech, violence, and cultural ignorance," and a "disproportionate targeting" of "Muslim women who wear hijabs, headscarves, or other religious articles of clothing...because of their religious clothing, articles, or observances." The resolution, H.Res.569 - Condemning violence, bigotry, and hateful rhetoric towards Muslims in the United States 
The legislation was cosponsored by Rep. Michael Honda, Rep. Keith Ellison, Rep. Joseph Crowley, Rep. Andre Carson, Rep. Eleanor Holmes Norton, Rep. Betty McCollum, Rep. Marcy Kaptur, Rep. Carolyn Maloney, Rep. Dan Kildee, Rep. Loretta Sanchez, Rep. Charles Rangel, Rep. Scott Peters, Rep. Brad Ashford, Rep. Alan Grayson, Rep. Mark Takai, Rep. Brian Higgins, Rep. William Keating, Rep. Raul Grijalva, Rep. Debbie Wasserman Schultz, Rep. G.K. Butterfield, Rep. Gerry Connolly, Rep. Ruben Gallego, Rep. Cheri Bustos, Rep. John Delaney, Rep. Kathy Castor, Rep. Luis Gutierrez, Rep. Michael Quigley, Rep. Elizabeth Esty, Rep. Joseph Kennedy III, Rep. Robin Kelly, Rep. Eddie Bernice Johnson, Rep. Gregory Meeks, Rep. Grace Meng, Rep. Al Green, Rep. Katherine Clark, Rep. Adam Schiff, Rep. Alcee Hastings, Rep. Sam Farr, Rep. Frank Pallone, Rep. Jim McDermott, Rep. Barbara Lee, Rep. Donna Edwards, Rep. Robert Brady, Rep. Frederica Wilson, Rep. Michael Doyle, Rep. Albio Sires, Rep. Suzan DelBene, Rep. Judy Chu, Rep. Jared Polis, Rep. David Loebsack, Rep. Bill Pascrell, Rep. Debbie Dingell, Rep. Jan Schakowsky, Rep. Steve Cohen, Rep. Ruben Hinojosa, Rep. John Yarmuth, Rep. Niki Tsongas, Rep. Jim Langevin, Rep. Mark Pocan, Rep. John Conyers, Jr., Rep. Mark Takano, Rep. Tim Ryan, Rep. Jose Serrano, Rep. Hank Johnson, Rep. Paul Tonko, Rep. Zoe Lofgren, Rep. Chris Van Hollen, Rep. Lois Capps, Rep. David Price, Rep. Doris Matsui, Rep. Gwen Moore, Rep. Denny Heck, Rep. Sheila Jackson Lee, Rep. John Carney, Rep. Xavier Becerra, Rep. Eric Swalwell, Rep. John B. Larson, Rep. Dina Titus, Rep. Peter Welch, Rep. Lloyd Doggett, Rep. Jim Himes, Rep. Matt Cartwright.
- [http://www.americanthinker.com/blog/2009/09/the_75_democrats_who_are_prose.html American Thinker, September 18, 2009 The 75 Democrats who are pro-sex slave ACORN defenders By Ethel C. Fenig]
- Invitation to Reception Honoring Martha Coakley, Jan. 12, 2010
- CLW website: Meet Our Candidates
- CLW website: Who We've Helped Elect
- Polis website. Polis, Cartwright Introduce Legislation to Hold Fracking Industry Accountable,
- J Street The political home for pro-Israel, pro-peace Americans
- JStreetPAC 2016 Endorsees
- American Political Action Committee,IAPAC Candidates, accessed January 29, 2017
- H.Res.569 - Condemning violence, bigotry, and hateful rhetoric towards Muslims in the United States, accessed December 26, 2015