President Donald Trump has signed a bill reopening the US Government, ending a 69-hour display of partisan dysfunction after Democrats reluctantly voted to temporarily pay for resumed operations.

Key points: Legislation to renew funding easily passes Senate and House

Legislation to renew funding easily passes Senate and House Donald Trump signs bill behind closed doors in the White House

Donald Trump signs bill behind closed doors in the White House Mr Trump says Democrats "have come to their senses"

The Democrats relented in return for Republican assurances that the Senate would soon take up the plight of young immigrant "Dreamers" and other contentious issues.

The vote set the stage for hundreds of thousands of federal workers to return, cutting short what could have become a messy and costly impasse.

The House approved the measure shortly thereafter, and Mr Trump later signed it behind closed doors at the White House, allowing Government to reopen through until February 8.

The measure needed 60 votes, and Democrats provided 33 of the 81 it got. Eighteen senators, including members of both parties, were opposed.

Most Democrats had initially opposed the funding bill, demanding that the Senate also approve protections for Dreamers.

Democratic leaders — worried about being blamed for a disruptive shutdown — accepted a Republican promise to hold a full Senate debate over immigration and the 700,000 Dreamers who were brought to the United States illegally as children.

Mr Trump's negotiations with Senate Democratic leader Chuck Schumer collapsed on Friday into recriminations and finger pointing and the deal to reopen the Government was cut without him.

The Republican President took a new swipe at Democrats as he celebrated.

"I am pleased that Democrats in Congress have come to their senses," Mr Trump said in a statement.

"We will make a long-term deal on immigration if and only if it's good for the country."

House Speaker Paul Ryan told Fox and Friends that if the Senate approved a temporary spending bill to reopen the Government, the House would approve it too.

Donald Trump signed the bill ending the three-day government shutdown in private. ( Supplied: White House )

Thousands of workers stay home

Tens of thousands of federal workers had begun closing down operations for lack of funding on Monday, the first weekday since the shutdown, but essential services such as security and defence operations had continued.

Health scientist Tom Chapel was among the many who spent the day at home after being furloughed from his job at the US Centres for Disease Control and Prevention in Atlanta.

"It was essentially a lunch break," Mr Chapel, who works at the US Centres for Disease Control and Prevention in Atlanta, joked.

What is a Dreamer? A child of unauthorised immigrants to the US

A child of unauthorised immigrants to the US Many have gone to school in the US and identify as American

Many have gone to school in the US and identify as American Takes its name from an unpassed 2001 bill that would allow pathway to US citizenship

Takes its name from an unpassed 2001 bill that would allow pathway to US citizenship Deferred Action for Childhood Arrivals (DACA) was designed to provide relief from threat of deportation

Deferred Action for Childhood Arrivals (DACA) was designed to provide relief from threat of deportation A two-year, renewable DACA authorisation allows for reprieve from deportation, work rights, drivers' licence and bank accounts Source: National Immigration Law Centre

"I'm a much more relaxed federal employee now that I have had a nice lunch break."

The shutdown undercut Mr Trump's self-crafted image as a dealmaker who would repair the broken culture in Washington.

It forced Mr Trump to cancel a weekend trip to his Mar-a-Lago estate in Florida and created uncertainty around his scheduled trip this week to the World Economic Forum in Davos, Switzerland.

The US Government cannot fully operate without funding bills that are voted on in Congress regularly.

Washington has been hampered by frequent threats of a shutdown in recent years as the two parties fight over spending, immigration and other issues.

The last US government shutdown was in 2013.

Tens of thousands of US federal workers begun closing down operations on Monday. ( AP: Alex Brandon )

Both sides in Washington had tried to blame each other for the shutdown.

While there was optimism from Senate Democratic leader Chuck Schumer that an immigration bill to protect Dreamers and bolster border security can pass the Senate, it was not clear that the more conservative House would accept such legislation.

In 2013, the Senate passed a bipartisan, comprehensive immigration bill only to see the House, controlled by Republicans, refuse to act.

Reuters/AP