The US government shutdown looked set to extend into a third week as senators again rejected a Republican funding bill on Thursday, despite US President Donald Trump's attempts to turn the thumbscrews on opposition Democrats.

Federal agencies have been out of money since October 1 and public services have been crippled amid stalled talks between the two sides, that have led to a series of near-daily failed votes to turn the lights back on.

With no sign of a breakthrough, Republican Senate Majority Leader John Thune indicated that a weekend session was unlikely, saying he was unsure "if that does any good," news website Semafor reported.

The Senate was due to be in session on Friday, with an eighth vote on the House-passed bill expected to fail.

Trump repeated his threats to slash government programmes popular with Democrats, as he berated the party over the shutdown at a cabinet meeting.

"The Democrat shutdown is causing pain and suffering for hardworking Americans, including our military, our air traffic controllers and impoverished mothers, people with young children, people that have to live not the greatest of lives," he said.

But his attempts to pressure Democrats to back the Republican bill – which would open the government through late November as negotiations continue – have so far fallen on deaf ears.

Democrats are privately preparing a shutdown lasting several more weeks, CNN reported, if Republicans do not agree to their demands to extend health care subsidies due to expire on December 31.

With some 750,000 federal workers "furloughed" – placed on enforced leave without pay – both sides have voiced concerns about the likelihood of military personnel missing their pay cheques next Wednesday. (AFP)