(CNN) Paul Manafort has reemerged as a player in the fight to shape the new administration, senior Republicans with knowledge of the transition tell CNN on Thursday, after resigning under pressure as the chairman of Donald Trump's campaign this summer.

Manafort solidified his ties to the incoming White House when Trump selected Vice President-elect Mike Pence as his running mate in mid-July. Both men are Capitol Hill veterans: Manafort as a lobbyist and Pence from his time as an Indiana congressman, with strong ties to the Republican establishment.

And with Pence firmly entrenched in Trump's inner circle alongside top strategist Steve Bannon, incoming Chief of Staff Reince Priebus and influential son-in-law Jared Kushner, Manafort -- who keeps a home in Trump Tower -- has a direct line to top decision-makers.

The image of an empowered Manafort, a longtime Washington operator with a murky slate of interests at home and abroad, would undercut Trump's pledge, already under fire given his early staffing choices, to "drain the swamp."

Trump spokesman Hope Hicks told CNN on Thursday that while staff contact with Manafort is "certainly not forbidden," he is "not involved in the transition team and is not in communication with the President-elect" and "definitively not involved in anything the President-elect is involved in."

Another source, who was considered for a cabinet position, also downplayed Manafort's role.

"Bannon, Reince, Pence and Jared are in the meetings," the source said. "Manafort and others offer opinions, but have little weight."

Still, the longtime K Street lobbyist and former Ronald Reagan operative has insinuated himself into the transition process through other channels, with allies like Rick Gates, who briefly served as the campaign's liaison to the Republican National Committee before leaving with Manafort in August, working behind the scenes on inauguration activities.

Manafort displaced Corey Lewandowski, Trump's inexperienced first campaign manager, in June after a protracted turf war and amid growing worries that the then-presumptive nominee would be challenged during a contested July convention.

He successfully navigated Trump through the Republican gathering Cleveland, but was ultimately sunk by growing questions about his foreign lobbying work, including ties to the pro-Russian former Ukrainian president Viktor Yanukovych -- and a summer swoon that saw Hillary Clinton jumping out to a double-digit lead in the polls.

Replaced by Bannon and Kellyanne Conway in late August, Manafort retreated from public view, but never fully exited Trump's orbit.