WASHINGTON — Rep. Conor Lamb is expected to launch a Senate campaign in August, according to three sources familiar with the Pennsylvania Democrat's decision.

Two sources said Lamb is planning a campaign event Aug. 6 at an International Brotherhood of Electrical Workers union hall in Pittsburgh, with one source noting that's where the congressman is expected to announce his Senate run. Multiple sources spoke on the condition of anonymity because they were not authorized by the campaign to speak publicly about Lamb's plans. Lamb's campaign did not respond to requests for comment.

Lamb, a Marine veteran and former prosecutor, will join a crowded primary field seeking to replace retiring GOP Sen. Patrick J. Toomey. Lamb would likely be the most moderate Democrat in the race, as he's known for a willingness to buck his party and work across the aisle. However, Lamb has been more likely of late to vote with a majority of Democrats on votes that split the parties.

Lamb's entry into the race also intensifies a geographic divide in the Democratic primary, with both Lamb and Lt. Gov. John Fetterman hailing from Western Pennsylvania.

Two other candidates, state Rep. Malcolm Kenyatta and Val Arkoosh, who chairs the Montgomery County Board of Commissioners, are based in the Philadelphia area in southeastern Pennsylvania, as is state Sen. Sharif Street, who is considering a Senate run.