Ed Gillespie, the former Republican National Committee chairman, lobbyist, and White House adviser under President George W. Bush, announced Thursday his bid for another prominent political title: U.S. senator from Virginia.

"I'm running for Senate because the American Dream is being undermined by policies that move us away from constitutional principles of limited government and personal liberty," Gillespie said in a video published online, wherein he also introduced his family and floated a platform based on replacing Obamacare and reducing the federal debt.

Gillespie will challenge Sen. Mark Warner, D-Va. — a former governor whose approval ratings have remained relatively robust during his Senate tenure, even as Democrats suffered nationally on issues like Obamacare.

For now, Gillespie's campaign will be low-key, reflected in its understated launch Thursday afternoon with the video and a website, EdForSenate.com.

Gillespie's path to the Republican nomination will not necessarily be free of conflict, and his early focus as a candidate will be shoring up support among moderate and conservative Republicans in advance of the nominating convention in June.

For the next few weeks, Gillespie will "begin working his way around commonwealth meeting with activists, with focus on winning [the] Roanoke convention," said a source with knowledge of his plans.

Gillespie will be able to lean on his well-curated network of Republican activists and donors he built as chairman of the state party as well as national party figures. Gillespie was a House aide for more than a decade, and later co-founded the mega-lobbying firm Quinn Gillespie and Associates with Jack Quinn, a Democrat. Gillespie was also a trusted adviser to George W. Bush and in 2003 took the reins at the Republican National Committee.

Although Gillespie is expected to mount a strong challenge to Warner, Gillespie's candidacy took many political watchers by surprise. Warner was not among the vulnerable Democrats listed as prime targets by the National Republican Senatorial Committee last year, and most Democrats did not expect that the Senate battle map would extend to Virginia.

That changes with Gillespie in the race, and Democrats will now need to commit resources to defending Warner — but they remain optimistic about their chances of keeping the Senate seat.

“Mark Warner is one of the most popular senators in the country and will be more than ready for whomever the Tea Party nominates to run against him, even if it’s a D.C. lobbyist like Ed Gillespie," said Justin Barasky, a spokesperson for the Democratic Senatorial Campaign Committee.