The Trump transition team has lost nearly half its staff and volunteers in a matter of days since instituting a ban on registered lobbyists at the end of last week, the Daily Mail has learned.

‘All the lobbyists are gone,’ said one source familiar with the transition. ‘Lobbyists were the vast majority. Now, today you go in and you could count [them] maybe on one hand.’

Mike Pence, the head of the transition team, touted the lobbyist ban as a sign of Trump’s commitment to change

The source estimated that the number of staffers and volunteers working on the transition plummeted from around 250 late last week to less than 125 on Tuesday. The sudden purge of lobbyists has allowed conservative think tanks like the Heritage Foundation and the Competitive Enterprise Institute to take a stronger role in the transition.

One lobbyist who was close to the transition team told the Daily Mail that ‘almost all of’ the lobbyists are gone from the team – although many are trying to influence as much as possible from the outside.

‘Everybody that’s still there has signed a letter saying they’ve deregistered and are okay with the five year ban,’ said the source. ‘It’s not like any transition I’ve ever seen before.’

Out! These three three high-profile lobbyists, from left, Michael Torrey, Michael Catanzaro and Mike McKenna - have been booted from the transition team

The mass exodus began late last week, after Trump officials asked transition workers to sign a form certifying that they were either not currently registered as lobbyists or foreign agents, or that they were in the process of terminating their lobbying registration. The form was due last Friday.

Donald Trump has repeatedly promised to ‘drain the swamp’ of Washington by cutting out special interests and lobbying groups from his administration. The departure of three high-profile lobbyists from the transition team -- Michael Torrey, Michael Catanzaro and Mike McKenna -- was reported last week.

Trump officials sent out an emails to transition staff last Thursday asking everyone to sign and return the certification forms by Friday.

The document verified that staffers were ‘not currently registered and reporting as a federal lobbyist…or as a compensated lobbyist at the state level in any state’ and were ‘not registered as an agent of a foreign principal.’

Individuals who were registered lobbyists and wanted to continue working for the transition had to certify that they had taken steps to terminate their status and promise to provide written evidence.

Vice president-elect Mike Pence, the head of the transition team, touted the lobbyist ban as a sign of Trump’s commitment to change on CBS on Sunday.

‘We made changes -- we moved lobbyists out of the transition team and that’s going to continue to be a lodestar,’ said Pence.

In! Transition officials - still with the team - were recently lobbyists or have only just deregistered, including, from left, Joel Leftwich, Rebecca Rosen and Joshua Pitcock

But some have questioned the effectiveness of the ban, pointing out that lobbyists often take advantage of loopholes that allow them to do their jobs without officially registering. Registered lobbyists are also continuing to advise the transition team in an unofficial capacity.

Others also pointed out that a number of transition officials - still with the team -were recently lobbyists or have only just deregistered, including Joel Leftwich, formerly with PepsiCo; Rebecca Rosen, previously with Devon Energy; and Joshua Pitcock, previously registered with the state of Indiana.

But insiders said the ban has had an undeniable impact inside the transition.

‘It’s beyond night and day the improvement,’ said a source familiar with the transition. ‘Lobbyists wanted to be around and schmooze, get to know people, help [their] buddies and members of congress get appointments. They did not really want to join the administration.’

‘Essentially, by just whacking all of the registered lobbyists, you now have think tank people,’ the source added.