Liberal icon Elizabeth Warren has emerged as the scourge of the Trump administration, grilling the president’s Cabinet nominees at every chance and coming out against Supreme Court pick Neil Gorsuch within minutes of his nomination.

The moves are what one might expect from a presidential aspirant. But Warren, who is placed in the top tier of likely Democratic 2020 candidates in very-early polls, first has to keep her Massachusetts Senate seat. It’s not a sure thing.

According to a WBUR poll, just 44 percent of state voters think she deserves re-election, while a plurality – 46 percent – believes she doesn’t deserve a second term. Overall, Warren has a 51 percent favorability rating in the deep blue state.

Republicans are ready to pounce – looking not only to reclaim the seat held, briefly, by GOP Sen. Scott Brown, but potentially sideline a future White House contestant.

“She is absolutely vulnerable. When she should be working for the people of the state, she is spending her time antagonizing the president,” Massachusetts Republican state Rep. Geoff Diehl, who is considering a 2018 Senate run, told Fox News. “She might as well be running for chairwoman of the Democratic National Committee.”

Diehl was co-chairman of President Trump’s Bay State campaign last year and gained statewide notoriety in 2014 leading a successful referendum to halt gas tax hikes.

Former Boston Red Sox pitcher Curt Schilling, a conservative talk radio host, also is considering running – though how serious, or viable, he is remains unclear. A Suffolk University poll last October found Warren leading Schilling by 58-24 percent.

A UMass Amherst poll last September found Warren would be in a statistical dead heat with either Republican Lt. Gov. Karyn Polito or former Republican Gov. Bill Weld – though it’s unlikely either Polito or Weld would run.

Presuming challengers emerge, an off-year election could be more difficult for Warren, said Donald Brand, a political science professor at the College of the Holy Cross in Worcester.

“Off-year elections are more of a challenge for Democrats nationwide,” Brand said.

He said he’s not betting against the incumbent, and expects out-of-state money to come to her aid. “Schilling is an iconic sports hero, comparable to Tom Brady, but he would have to be a lot more disciplined to run a viable campaign,” Brand said. “I would anticipate that the Democratic elite nationally would rally to her if it’s a tight race.”

The consequences of a bruising, even losing, Senate race, though, could be profound for her political future. “It would be a national embarrassment if she were defeated. Even if she wins and it’s a close election, she’s much weaker going into 2020,” Brand said.

A December Public Policy Polling survey of potential Democratic candidates for 2020 found Warren in third place behind former Vice President Joe Biden and Vermont Sen. Bernie Sanders, who ran unsuccessfully against Hillary Clinton for the 2016 nomination. But when Democrats picked a 2020 candidate in a pre-2016 election poll conducted by Politico/Morning Consult, Warren led, beating her closest opponent -- Virginia Sen. Tim Kaine -- by 12 points.

Brand noted that Trump is likely to be unpopular in a state like Massachusetts during the first midterm, which could help Warren, who first won the seat in 2012 by defeating Brown.

Warren continued to frame herself as a fighter in her January re-election announcement. “The people of Massachusetts didn’t send me to Washington to roll over and play dead while Donald Trump and his team of billionaires, bigots and Wall Street bankers crush the working people of our Commonwealth and this country,” Warren’s statement said.

Reached for comment, Warren’s Senate office referred Fox News to the state Democratic Party – which maintained confidence about her chances.

“There are plenty of powerful, corporate interests, rolling in dough, eager to attack Elizabeth Warren, but that’s never stopped her before and it’s not going to stop her now,” party spokeswoman Emily Fitzmaurice said. “More than ever, we need Elizabeth working to level the playing field for the people of Massachusetts and working families all across our country.”

Massachusetts GOP Chairwoman Kirsten Hughes sent a fundraising email highlighting the WBUR poll to assert, “voters are sick of Elizabeth Warren and they want fresh, new leadership. …Voters clearly see that Warren's hyper-partisan, extremist rhetoric does nothing for our state, and serves only to isolate her in D.C.”

Popular Republican Gov. Charlie Baker also is up for re-election next year. So, could a flood of Democratic money in the state for the Warren race actually hurt what could otherwise be an easy race for Baker? Diehl doesn’t think so.

“The people of Massachusetts are very politically attuned and are able to split state and national races,” Diehl said. “At the same time, I think it would benefit the governor to have a strong opponent taking on Elizabeth Warren.”