Appointees to President-elect Donald Trump's administration will be asked to sign a form barring them from being a registered lobbyist for five years after they leave government service, officials announced Wednesday -- following up on the D.C. outsider's pledge to "drain the swamp."

Republican National Committee chief strategist Sean Spicer said on a conference call with reporters that the prohibition would help to ensure people won't be able to use government service "to enrich themselves."

In addition, Spicer announced that Trump transition team members would be barred from lobbying about the issues they had worked on for six months after their departure. He did not immediately explain how either ban would be enforced.

The new Trump transition policy is one of several aimed at curbing the influence of lobbyists. During the presidential campaign, Trump vowed to institute a five-year lobbying ban for all departing members of Congress and their staff, in addition to executive branch officials.

His original transition team, assembled under New Jersey Gov. Chris Christie, was packed with lobbyists and interest advocates. In recent days, Trump put Vice President-elect Mike Pence in charge of transition, and he is changing some of the people who are involved.

Pence is "making good on President-elect Trump's promise that we're not going to have any lobbyists involved with the transition efforts," Trump spokesman Jason Miller said Wednesday. "And this is, when we talk about draining the swamp, this is one of the first steps. And so, the bottom line is, we're going to get the transition team where we need it to be."

In a "60 Minutes" interview that aired Sunday, Trump said he'd had no choice but to initially rely on lobbyists in Washington because "the whole place is one big lobbyist." He vowed to "phase that out."

His White House predecessors have made similar promises.

On the campaign trail in 2007, Barack Obama frequently condemned the "revolving door" of Washington in terms strikingly similar to Trump.

When Obama won the presidency the following year, he banned practicing lobbyists from participating in transition activities and banned those who had been a lobbyist in the previous year from joining the administration to work on issues they handled as lobbyists. Obama's transition team participants were also barred from lobbying the White House for a year after their departures.

With government influencers still firmly entrenched, Obama won re-election in 2012 after a second campaign that included almost no talk about the revolving door.

The Associated Press contributed to this report.