Donald Trump's campaign pledge to "drain the swamp" in Washington and save taxpayers money will see many federal government jobs left unfilled, according to US budget director Mick Mulvaney.

But a hiring freeze implemented by the US president as one of his first acts in office will be lifted, he said.

“This is a big part of draining the swamp,” he added, echoing a repeated Trump campaign promise to rid Washington of wasteful spending and entrenched politicians.

He added that although the hiring freeze had been lifted it did not mean that government agencies "will be free to hire willy-nilly."

He said. "What we're doing tomorrow is replacing the across-the-board hiring freeze that we put into place on Day One in office and replacing it with a smarter plan, a more strategic plan, a more surgical plan."

Shortly after taking office in January, Mr Trump signed a memorandum freezing large portions of federal government hiring, while exempting the military and positions deemed necessary for national security and public safety.

As part of the memorandum, he gave Mr Mulvaney's Office of Management and Budget. 90 days to come up with a long-term plan to reduce the federal government's size.

Agency directors have received their workforce reduction instructions based on Mr Trump’s proposed federal budget which makes cuts to several domestic departments and includes a $54bn (£43bn) increase to military and national security spending.

The controversial orders Donald Trump has already issued Show all 9 1 /9 The controversial orders Donald Trump has already issued The controversial orders Donald Trump has already issued Trump and the media White House Press Secretary Sean Spicer takes questions during the daily press briefing Getty Images The controversial orders Donald Trump has already issued Trump and the Trans-Pacific Partnership Union leaders applaud US President Donald Trump for signing an executive order withdrawing the US from the Trans-Pacific Partnership negotiations during a meeting in the Roosevelt Room of the White House in Washington DC. Mr Trump issued a presidential memorandum in January announcing that the US would withdraw from the trade deal Getty The controversial orders Donald Trump has already issued Trump and the Mexico wall A US Border Patrol vehicle sits waiting for illegal immigrants at a fence opening near the US-Mexico border near McAllen, Texas. The number of incoming immigrants has surged ahead of the upcoming Presidential inauguration of Donald Trump, who has pledged to build a wall along the US-Mexico border. A signature campaign promise, Mr Trump outlined his intention to build a border wall on the US-Mexico border days after taking office Getty Images The controversial orders Donald Trump has already issued Trump and abortion US President Donald Trump signs an executive order as Chief of Staff Reince Priebus looks on in the Oval Office of the White House. Mr Trump reinstated a ban on American financial aide being granted to non-governmental organizations that provide abortion counseling, provide abortion referrals, or advocate for abortion access outside of the United States Getty Images The controversial orders Donald Trump has already issued Trump and the Dakota Access pipeline Opponents of the Keystone XL and Dakota Access pipelines hold a rally as they protest US President Donald Trump's executive orders advancing their construction, at Columbus Circle in New York. US President Donald Trump signed executive orders reviving the construction of two controversial oil pipelines, but said the projects would be subject to renegotiation Getty Images The controversial orders Donald Trump has already issued Trump and 'Obamacare' Nancy Pelosi who is the minority leader of the House of Representatives speaks beside House Democrats at an event to protect the Affordable Care Act in Los Angeles, California. US President Donald Trump's effort to make good on his campaign promise to repeal and replace the healthcare law failed when Republicans failed to get enough votes. Mr Trump has promised to revisit the matter Getty Images The controversial orders Donald Trump has already issued Donald Trump and 'sanctuary cities' US President Donald Trump signed an executive order in January threatening to pull funding for so-called "sanctuary cities" if they do not comply with federal immigration law AP The controversial orders Donald Trump has already issued Trump and the travel ban US President Donald Trump has attempted twice to restrict travel into the United States from several predominantly Muslim countries. The first attempt, in February, was met with swift opposition from protesters who flocked to airports around the country. That travel ban was later blocked by the Ninth Circuit Court of Appeals. The second ban was blocked by a federal judge a day before it was scheduled to be implemented in mid-March SANDY HUFFAKER/AFP/Getty Images The controversial orders Donald Trump has already issued Trump and climate change US President Donald Trump sought to dismantle several of his predecessor's actions on climate change in March. His order instructed the Environmental Protection Agency to reevaluate the Clean Power Plan, which would cap power plant emissions Shannon Stapleton/Reuters

Their departments will be be required to come up with a plan by 30 June that will “maximize employee performance” and a longer-term plan by September.

Ed Lorenzen, Senior Advisor at the Washington DC non-profit Committee for a Responsible Federal Budget, told The Independent that he think Mr Mulvaney made the announcement about the hiring freeze being lifted because it has caused problems in programs and activities the administration considers important "such as processing Veterans Administration disability claims.”

The seemingly conflicting announcement possibly “provid[es] flexibility” to the administration to replace departing workers in programmes they want to continue while reducing overall workforce because agencies have also been asked to identify programs that can be completely eliminated, he said.

He estimated the proposed budget and workforce reduction would save the federal government approximately $1.2 billion (£960m) in the first year and $50bn (£40bn) over ten years, based on data from the independent Congressional Budget Office and “attrition, which we assumed would entail replacing federal employees at a rate of 1 for every 3 workers that retire.”

A former defence department employee however told The Independent, that the announcement is a blow to employee morale, especially to those “the lowest on the totem pole.”

He said “even rumours cause people to produce less because they think they are about to be cut.”

Less productivity gives agency directors, who are political appointees, more justification to eliminate or drastically cut programs, he added.

“Just let attrition occur naturally,” he said, adding that they think the administration’s proposed slashing of budgets in certain agencies and retirement rates will be enough to get people to leave federal employment.