A key Democratic lawmaker on Monday vowed to significantly ramp up his efforts to build support for bipartisan legislation that would shield special counsel Robert Mueller from political interference, amid renewed attacks on the Russia investigation from President Donald Trump and his legal team.

“Unfortunately, the statements and actions from the president and his lawyer over the weekend have led me to believe that the special counsel is now at real, immediate risk of being removed, and I believe the Senate needs to pass legislation to ensure that does not happen,” Sen. Chris Coons (D-DE) said.

Coons, one of the chief architects of a bipartisan bill that would institute judicial review for any attempt to fire a special counsel, said he plans to “speak individually with as many of my colleagues as possible to build support for this effort.”

But the new push comes as many Democrats have already resigned themselves to the fact that despite Trump’s and his lawyer’s most recent attacks on the special counsel’s investigation, which have escalated the months-long efforts from the president and his allies to discredit the probe, Republicans and their leaders on Capitol Hill aren’t on board with a legislative response—prompting some to look for other avenues to preserve Mueller’s investigation.

Aside from legislation, lawmakers have begun discussing joint letters or floor speeches as a way to “send a strong signal” to Trump.

“I’m hopeful that we can make progress on that bill,” Coons told The Daily Beast. “I just had a number of conversations on the floor, and I think there are several senators in both parties who are looking for ways to convey to the president how seriously we take the threats to the special counsel.”

Democrats’ frustrations with the lack of progress on legislation come as Republicans remain unconvinced that Trump would actually move to thwart or end Mueller’s investigation—despite heightened attacks on the probe, which is looking into Russian election meddling and possible Trump-Russia collusion. They’ve relied instead on the White House’s insistence that Trump is not considering taking such action, and some have cited conversations with the president or his staff to conclude that Mueller isn’t in any real danger.

“I’m not worried about it at all,” Senate Majority Whip John Cornyn (R-TX) said. “I think it’d be a big mistake and I think that’s the kind of advice he’s getting from everybody. … The consequences would be so overwhelming that it’s just not going to happen.”

The president and his legal team continued over the weekend to toughen their posture toward the special counsel’s investigation. On Saturday, John Dowd, a lawyer on the president’s team, told The Daily Beast that the probe should be shut down. While Dowd later said he was speaking only for himself, Trump followed suit in a series of tweets later that same day attacking the integrity of the probe. And on Monday, Trump’s legal team brought on Joseph diGenova, who has pushed a conspiracy theory about the president being “framed” by the FBI and the Justice Department.

In January, Coons’ Republican counterpart, Sen. Thom Tillis (R-N.C.), appeared to back off his own legislation to protect Mueller’s probe. Daniel Keylin, a spokesman for the senator, told The Daily Beast at the time that “the president and his administration have spoken favorably of Special Counsel Mueller’s professionalism and integrity,” and that talk of firing Mueller “has completely come to a halt.”

On Monday, Tillis joined the Republican chorus of support for Mueller’s investigation in the aftermath of Trump’s tweets deeming it a “witch hunt” that “should never have been started.” But Tillis said that there wasn’t an “imminent need” to pass his legislation “today or this week,” as some lawmakers have floated the possibility of adding special counsel protection language to the massive spending bill Congress is considering this week. Eventually, Tillis said, the legislation should move forward “as a matter of good governance.”

Many of his Republican colleagues disagree. Sen. Lindsey Graham (R-S.C.), who co-authored a separate piece of legislation with Sen. Cory Booker (D-N.J.) aimed at protecting Mueller, has also backed away from his own bill in recent months, saying he remains confident that Trump wouldn’t move against the special counsel.

“I’m not at all [concerned]. That’s exactly what they did with Ken Starr,” Graham said on Monday, referring to the independent counsel who investigated President Bill Clinton. “Democrats went after Ken Starr saying it’s a witch hunt. Nobody talked about firing Ken Starr. And unless there’s some reason to fire Mueller, that's not going to happen. And I don’t see a reason—but you can expect Trump and other folks to go after Mueller. Democrats went after Ken Starr.”

When asked why he introduced legislation in the first place, Graham responded: “Just to let people know where I stand.”

Even some of the president’s most hardened critics aren’t on board with a legislative response. Sen. Jeff Flake (R-AZ) said he has constitutional concerns with the two bills being considered, but thinks Republican leadership should preemptively speak out against a Mueller firing more forcefully than they have in the past.

“Some of us have spoken out. Everybody needs to—strongly. I would hope that our leadership would come out and say this is a red line you can’t go past,” Flake said. “If you’re going to pick a fight, this is a fight to pick. You’ve got to pick this fight. If you don’t pick this fight, we might as well not be here. This is a serious one.”

A few Republican lawmakers did speak out more aggressively in the aftermath of the White House offensive this weekend, with Rep. Trey Gowdy (R-S.C.) saying: “If you have an innocent client, Mr. Dowd, act like it.” Others echoed Gowdy, arguing that Trump shouldn’t attack the investigation if he truly believes he is innocent.

Sen. Chuck Grassley (R-IA), the chairman of the Senate Judiciary Committee, said that “the best thing for him as president—since after almost one year there’s been no show of collusion—it seems to me like he’s coming out looking pretty good at this point and that he ought to just let it play out.”

Grassley’s panel has been working for months to reconcile the two bills intended to protect Mueller’s probe into one, but that effort appears stalled.