Editor's note: This story has been updated throughout.

Congressional candidate MJ Hegar fired back Thursday at U.S. Rep. Henry Cuellar, a fellow Democrat, for participating in a fundraiser earlier this week for her opponent, Republican U.S. Rep. John Carter of Round Rock.

"I think that Congressman Cuellar does a good job of working across the aisle and working in a bipartisan way," she said in an interview with the Texas Tribune's Evan Smith. "I think that raising money for somebody who doesn't represent your values ... that's different. That actually is going against the values that you're trying to fight for."

On Tuesday, reports surfaced that Cuellar participated in a fundraiser for Carter in San Antonio. Cuellar released a statement later in the day downplaying the significance of the action, arguing that he frequently attends events with members who visit his district and added that "friendship is more powerful than partisanship."

Hegar, a decorated Air Force veteran, is challenging Carter in Texas' solidly red 31st Congressional District, which runs north of Austin and up to Fort Hood.

While stressing she has "nothing against Congressman Cuellar," Hegar questioned whether such actions were actually bipartisan.

"I'm a huge fan of bipartisanship and working together to get things done," Hegar said. "I do think there's a difference, though, between the friendship that belongs on the golf course and fighting for our ideals and values on the battlefield. And I think it's actually not an example of bipartisanship. I think it's actually an example of what's wrong with politics today."

She added that, over the course of her campaign, she has reached out to all of the Texas Democratic members of Congress but never heard back from Cuellar.

"So, he and John Carter have that in common, that they don't return my phone calls," she said.

"It's a little bit good old boys club, maybe. Maybe. It's a little clubby," she said. "It's a little, 'I'm going to put my personal interests and my personal feelings and my personal relationships and my ego and my resume and my future ahead of the values the people who voted for you put you there to fight for.'"

"I have long-since said that working ... together and accomplishing things in a bipartisan way doesn't mean compromising your values," she added.

When asked about Hegar's comments Thursday, Cuellar said, "MJ Hegar is a genuine American hero and our entire country owes her a debt of gratitude."

Bruce Harvie, a spokesman for Carter's campaign, said Carter and Cuellar have a long history of working together to help their constituents.

"It's unbelievable that Ms. Hegar would criticize them for putting the people of their district ahead of their party," Harvie said. "Comments like that show Ms. Hegar’s liberal, partisan philosophy and go to show that Ms. Hegar will be nothing but a loyal rubber stamp for Nancy Pelosi and the Democratic Party instead of working with both parties to get things done."

Hegar launched her bid against Carter last summer. While drawing skepticism that a Democrat could win the Republican-leaning district, she has blown Carter away in fundraising this year and is currently on television with campaign ads in the district. National Republicans are cautiously watching polling to see if they need to enter the fray and offer financial support for Carter's re-election bid.

Carter is ramping up his campaign after Hegar roared through the summer with national attention and raised massive amounts of money.

On that front, Hegar predicted in Thursday's Tribune interview that she will have a strong third quarter and again report outraising Carter. That strong fundraising is an important factor in her ability to win the election, she argued.

"Money is not everything, but money is a big part in how we talk to voters in a district this size," Hegar said. "You can’t do it all on door knocking."

Since 2002, the best a Democrat has done against Carter is to lose by 19 points. Despite this, Hegar said the district is still winnable for a Democrat if she can draw out new voters as well as win the support of some who voted in this year’s Republican primary.

That last part is doable, she said, because of the nature of Texas’ open primary system, which allows voters to decide at the last minute which primary they are going to vote in.

“I’ve voted in a Republican primary in the past,” Hegar said. That’s something unique to Texas and a handful of other states, that we don’t register as Republicans or Democrats. We vote in whichever primary we think it’s more critical at the time.”

Besides energizing women, veterans and the Democratic base, Hegar predicted that the key to winning her race will be her giving the district’s voters a compelling reason to support her.

“My district doesn’t come to vote to the polls against something because they fear something,” Hegar said. “They will come to the polls to vote for something because they are inspired by something.”

Omar Rodriguez-Ortiz contributed to this report.