State Sen. Jennifer Wexton (D-Loudoun) is seeking the Democratic nomination to challenge Rep. Barbara Comstock (R-Va.) in the 2018 mid-term elections. ( Jennifer Wexton campaign)

State Sen. Jennifer Wexton will announce Thursday she is seeking the Democratic nomination to challenge Rep. Barbara Comstock (R) in a northern Virginia district that President Donald Trump lost last year.

Many Democrats consider Wexton, a former prosecutor from Loudoun County, the strongest candidate in a field of hopefuls who would stand out in a typical year.

A wave of liberal activism galvanized by Trump’s election convinced Wexton she could unseat Comstock despite the congresswoman’s success in competitive races.

“The grassroots energy is so inspiring,” she said in an interview at her Leesburg home on Wednesday. “I’m seeing all these people who are resisting and persisting and doing what they can to hold their representatives accountable. And this is something I can do. I can help by helping to hold Barbara Comstock accountable.”

Democrats say they expect Wexton to capi­tal­ize on her experience in public office and roots in Loudoun County, the heart of the district home to a savvy, diverse electorate courted by both parties.

She spent about $472,000 in her 2015 reelection to the legislature but will have to raise millions to compete against Comstock, a fundraising powerhouse and relentless campaigner. Outside groups will likely pour resources into campaigns on both sides.

Last year Comstock won a nationally watched race by 6 points — and outperformed Trump by 16 — by focusing on local issues such as transportation and opioid abuse.

With the only congressional district in the D.C. metropolitan area that could be considered a swing district, Comstock has withstood pressure from constituents and others to hold an in-person town hall. She prefers large-scale conference calls with residents.

Wexton said she has held four traditional town halls since February, including one with Del. J. Randall Minchew (R-Loudoun) that drew 150 residents.

“Closely controlled, scripted town halls don’t count,” she said. She added later: “This year people are actually paying attention. People can see when she’s paying lip service to issues but how she’s really voting when it counts.”

Wexton pointed to Comstock’s support for a House rules package that allows lawmakers to reduce the salary of any federal worker to $1, and her multiple votes to repeal the Affordable Care Act, which provides benefits to opioid addicts.

Picking up on the theme of LuAnn Bennett’s failed campaign to unseat Comstock last year, Wexton referenced the “Trump-Comstock agenda” twice in an hour.

She is the fourth Democrat to declare her intentions. Also running are Daniel Helmer, an Army veteran, Lindsey Davis Stover, a former Obama administration official, and Kimberly Adams, past president of the Fairfax teacher’s union. Several others are considering jumping in, including Dorothy McAuliffe, the wife of Gov. Terry McAuliffe.

Wexton, 48, grew up Bethesda, and earned a bachelor’s degree at the University of Maryland and a law degree at William and Mary.

She started work in 2001 as an assistant commonwealth’s attorney in Loudoun County, where she tried cases from homicide to domestic abuse. In a high-profile 2002 trial, Wexton successfully prosecuted Clara Jane Schwartz, a college student accused of orchestrating her father’s slaying.

After about five years, she went into private practice but continued to serve as a court-appointed attorney representing children in abuse and neglect cases and parties to mental health commitment hearings; she later served as a substitute judge in Loudoun County.

She resigned to challenge Jim Plowman, the Loudoun commonwealth’s attorney, in 2011. She lost by about 2,000 votes in a year when Republicans swept the board of supervisors.

Then, Mark Herring left the state senate to serve as attorney general. Wexton ran in the January 2014 special election for his seat and won by 14 points.

At the time, Democrats were reeling from the transvaginal ultrasound debate, the repeal of the limit of handgun purchases to one a month and new voter ID laws, and her race was one of two that determined which party controlled the state Senate.

The following year, she won a full term. She does not need to give up her seat in the legislature to run for Congress.

She and her husband moved to the congressional district in 2004. They live in Leesburg with their two sons and two rescue labrador retrievers.