RENO, NV - APRIL 17: Sen. Dean Heller (R-NV) speaks at a town hall with Rep. Mark Amodei (R-NV) inside the Reno-Sparks Convention Center on April 17, 2017 in Reno, Nevada. Heller and Amodei spoke with constituents for over two hours on key issues including immigration reform and healthcare. (Photo by David Calvert/Getty Images)

Nevada Republican Sen. Dean Heller’s closely watched re-election bid heated up Tuesday with Democratic officials saying freshman Rep. Jacky Rosen will contest him in 2018.

No other challengers have entered the race and Rosen, a former computer programmer and president of a Henderson synagogue, has not officially declared her candidacy.

Democrats aiming to upset the GOP’s Senate majority consider Heller’s seat the most vulnerable. The state voted for Democrats in the last three presidential elections and changing demographics are steadily increasing the party’s advantages in statewide races.

Heller’s ties to President Donald Trump’s policies have not received a warm welcome at town halls and rallies in his home state and Democrats are aiming to capitalize on that anger.

Several Democratic campaign officials in Nevada and Washington, speaking on condition of anonymity ahead of an official announcement, said Rosen is gearing up for a U.S. Senate campaign. They expect her to run.

State GOP Chairman Michael McDonald called Rosen self-serving and untrustworthy for moving quickly up the political ranks with her expected candidacy, saying she is “just in it for herself” if she challenges Heller.

Rosen’s spokeswoman Ivana Brancaccio did not return calls or emails seeking comment.

Rosen’s personal website and social media pages offer no contact information. Her staff assistant in Washington, Chelsea Rosenberg, declined on behalf of the congressional office to comment or to provide any current campaign contacts.

Former Sen. Harry Reid chose Rosen to run for Nevada’s toss-up, southernmost congressional district after other Democrats turned down the 2016 contest. She narrowly won and took office in January.

“Reid cleared the field for Rosen in 2016 and has done so again,” Greg Bailor, executive director of the state GOP, said in an emailed statement Tuesday. “If she decides to run for Senate that is a pretty self-serving and ambitious jump.”

Heller campaign spokesman Tommy Ferraro said it was only a matter of time before Reid and Senate Minority leader Chuck Schumer designated a liberal challenger. “We look forward to Nevadans deciding between a handpicked Harry Reid candidate and the independent leadership of Dean Heller,” Ferraro said in an emailed statement.