Virginia Lt. Gov. Ralph S. Northam talks with Tahqualan Brooks, 8, from Colonial Beach, on Nov. 14, 2015. Northam was volunteering at a free health clinic in Virginia’s Northern Neck. (Reza A. Marvashti / For The Washington Post)

Lt. Gov. Ralph S. Northam (D) on Tuesday officially announced that he is running for Virginia governor in 2017.

“As a former Army doctor and practicing pediatric neurologist, I know that the best way to serve people is to listen to their needs and concerns,” Northam said in an e-mail sent to supporters. “And as a public official, I’ve taken the same approach to serving our Commonwealth.”

Northam quietly began informing supporters early this year that he planned to run and confirmed his intentions when word leaked in February.

At the time, Northam was expected to face a tough primary battle with Attorney General Mark R. Herring (D), then considered the front-runner for the Democratic nomination because of his high-profile actions on same-sex marriage and other issues dear to the party’s liberal base. But Herring later announced that he would run for reelection instead, seeming to clear the field.

Northam is a former state senator who won the office of lieutenant governor in 2013, completing a Democratic sweep of statewide offices with Herring and Gov. Terry McAuliffe. Northam has worked closely with McAuliffe, and his candidacy is believed to be viewed favorably by the term-limited governor.

Northam could still face competition for the nomination. No other Democrats have said they will run since Northam confirmed his plans to do so in February. But other names have been floated, including that of Rep. Gerald E. Connolly (D).

On the Republican side, former White House counselor and Senate candidate Ed Gillespie has announced plans to run. He established a political action committee last week.

Former attorney general Ken Cuccinelli II (R), who narrowly lost to McAuliffe in 2013, has not ruled out a run in 2017. Several other conservative Republicans have hinted that they might seek the nomination, currently set to be determined at a party convention — a forum that tends to favor conservative candidates.

Northam has been a low-key but well-liked figure in Richmond, drawing on his Eastern Shore roots and folksy manner to find common ground with rural Republicans. Early in his state Senate tenure, he broke with his party over a judicial nomination. The GOP tried to persuade him to switch parties, but Northam stuck with the Democrats.

Despite his moderate style, Northam hits on some hot-button issues in his announcement, including abortion and expanding access to Medicaid under the Affordable Care Act. Democrats are likely to play up partisan issues in an effort to turn out voters in the off-year gubernatorial election.

“In the two years I’ve been Lieutenant Governor, we’ve been able to make great strides,” Northam said in the announcement. “We’ve expanded access to affordable health care, created over 40,000 jobs, and opened up pre-K to thousands of young Virginians. I’ve broken ties on Senate votes in favor of increasing the minimum wage, banning discrimination in the workplace, and repealing the invasive ultrasound mandate.

“But . . . there’s still much more we want to do for the Commonwealth. We need to continue investing in early childhood education, creating jobs in the New Virginia economy, protecting women’s reproductive rights and expanding access to Medicaid for 400,000 of our citizens.”