The popular progressive US senator Bernie Sanders would consider supporting any Democrat who might mount a challenge against his chamber colleague Kyrsten Sinema after she recently left the party and declared herself an independent like him, arguing that she has “helped sabotage” some of Congress’s most important legislation.

Sanders’s comments on Sunday on CNN’s State of the Union added to the chorus of detractors against the Arizona lawmaker who has undermined the agenda of the Joe Biden White House and other progressives, including by voting down raising the minimum wage to $15 an hour and reforming the Senate filibuster so that voting rights legislation can pass.

The independent from Vermont who votes in line with Democratic interests told the show host, Dana Bash, that the leftwing party’s members in Arizona were “not all that enthusiastic about somebody who helped sabotage some of the most important legislation that protects the interests of working families and voting rights and so forth”.

And, Sanders added, if Arizona Democrats eventually ran someone to challenge the newly-declared independent, “I will take a hard look at” supporting that candidate, though some are concerned that hopeful could unwittingly give Republicans an opening.

“I support progressive candidates all over this country – people who have the guts to take on special interests,” said Sanders, adding that he wasn’t interested in speaking much more on Sinema. “I don’t know what’s going to be happening in Arizona – we will see who they nominate.”

In a separate pre-recorded interview which also aired Sunday on State of the Union, Sinema continued defending her defection from the Democrats as a stand against being beholden to party interests.

“I know this is really hard for lots of folks, especially [on Capitol Hill], but what’s important to me is … to not be tethered by the partisanship that dominates politics today,” Sinema said in that interview. “I want to remove some of that … poison from our politics. I want to get back to actually just working on the issues, working together to try and solve these challenges.”

Sinema’s departure from the Democrats came after their party had just succeeded in getting every one of their senators re-elected for the first time since 1934 after Raphael Warnock retained his seat in Georgia on 6 December.

Warnock’s victory over Republican challenger Herschel Walker, combined with a Pennsylvania seat flipping to the Democrats, left his party thinking it had a clear one-seat majority in the upper congressional chamber. It had spent the past two years with a 50-50 split in the Senate in which Vice-President Kamala Harris broke ties in the Democrats’ favor.

Sinema, who entered politics as a Green Party member and antiwar activist, has said she doesn’t intend to caucus with Republicans. But she’s been vague about whether she would cooperate with the Democrats in the way that Sanders and fellow independent senator Angus King do.

Sinema has supported key Biden administration agenda items, including bills aimed at reducing inflation, protecting the right to gay marriage and increasing restrictions to high-powered guns. But her votes against a minimum wage raise and Senate filibuster reform – issues that were dear to the Democrats – have earned her scorn from many progressives.

She and the centrist West Virginia Democratic senator Joe Manchin, who has taken similar stands, are often mentioned in the same breath.

Sinema announced her switch after a Democratic member of the House of Representatives from Arizona, Ruben Gallego, had started interviewing paid media firms for 2024, which observers interpreted as a meaningful step toward launching an intra-party primary challenge.

Pundits believe the Democrats could risk splitting votes with Sinema if they run someone against her, giving Republicans an opportunity to flip that seat during an election that would unfold at the same time as the next presidential race.