Democratic Rep. Jacky Rosen, a former software programmer and synagogue president, announced Thursday she will seek the Senate seat held by Dean Heller, who political analysts rate as the chamber’s most vulnerable Republican in the 2018 campaign.

“Now more than ever, Nevadans deserve a senator they can trust to be an independent voice standing up to President [Donald] Trump, not his enabler,” the first-term congresswoman said in a statement. Heller “might not sound like President Trump, but his voting record shows he supported Trump’s agenda 100% of the time in his first 100 days.”

Rosen, a political newcomer, defeated GOP businessman Danny Tarkanian last November in Nevada’s 3rd Congressional District, which encompasses the state’s southern tip. She was urged to challenge Heller by former Democratic Sen. Harry Reid, the party leader who retired last year, Rosen told The Nevada Independent.

Rosen’s entry into the Senate race comes as Heller faces intense political pressure ― from both the left and the right ― over his stance on the Republican efforts to repeal and replace Obamacare. Heller quickly announced that he opposed the health care bill unveiled by Senate Majority Leader Mitch McConnell (R-Ky.) late last month, joining a handful of other of GOP senators whose criticism of the legislation sidetracked a vote on it.

A pro-Trump political group responded by launching television ads attacking Heller for his position, a matter that he brought up in a meeting with the president and other senators at the White House. Heller’s full-throated criticism of the bill, however, hasn’t placated Democrats, who have attacked him for previously voting to undo Obamacare and roll back its Medicaid expansion.

In her interview with the Independent, Rosen called Obamacare “far from perfect” and said it ought to be fixed rather than repealed. She called a single-payer health care system an “interesting idea” that she might consider supporting if it was part of a larger health care plan.

“I can’t stand by and watch while President Trump and Senator Heller leave middle-class families stranded,” Rosen, 59, said in her Thursday statement. “I want to be a champion for all Nevadans, and this is a critical opportunity to make an even bigger difference for the state I’ve called home for nearly 40 years.”

Reid’s handpicked successor, Democratic Sen. Catherine Cortez Masto, endorsed Rosen’s bid on Thursday.

I need Jacky Rosen with me in the Senate to fight back against Trump’s dangerous agenda and stand up for Nevada’s families,” she said in a statement. “She is a friend and will make an excellent senator for the Silver State.”

Still, Rosen could face a fight for her party’s Senate nomination from another leading Nevada Democrat, Rep. Dina Titus, 67. Signaling her interest in the race, Titus contrasted her record with that of Rosen’s on Wednesday.

“Jacky Rosen is a nice lady,” she told the Las Vegas Sun. “She is new to politics. Maybe that has some appeal. People might want somebody who has not been part of the process. But I am proud of my record, and I think Nevada has got some really tough fights and needs somebody who is seasoned in the ring.”

Titus first won election in Nevada’s 1st Congressional District, which comprises Las Vegas, in 2008. She lost her seat in 2010, but won it back in 2012.

Heller, 57, was appointed to the Senate in 2011, replacing scandal-plagued Republican John Ensign, who had resigned. Heller narrowly held onto the seat in the 2012 election.