US verge of shutdown
US House speaker John Boehner departs after a closed-door meeting of the House Republican caucus (Reuters)

A government shutdown looms in the US as the Republicans in the House of Representatives remain at loggerheads with the Democrats over the Senate-approved bill on healthcare.

The Republican-led House has passed a modified version of the Senate bill along with pushing for a one-year delay in President Barack Obama's healthcare reform law, better known as "Obamacare".

With less than 48 hours left to pass the expenditure bill, no agreement between the two sides is in sight. The Senate will not convene until Monday (30 September).

US Senate Majority leader Harry Reid has already threatened to reject the amended bill. Dubbing the Republican move as "pointless", Reid said "after weeks of futile political games from Republicans, we are still at square one".

Obama has earlier said he would veto the Republican bill.

White House spokesperson Jay Carney said: "Any member of the Republican Party who votes for this bill is voting for a shutdown."

Despite the veto threat, the Republicans voted 231 to 192 for the modified version of the bill.

If the collision course reaches its logical conclusion, it will be the first US government shutdown in 17 years.

"House and Senate like two locomotives barrelling toward one another ... in slow motion," Republican Scott Rigell wrote on his Twitter account.

If the shutdown does take place on 1 October, nearly a third of its employees will stop working, crippling essential services like air traffic control and food inspection.

According to the Anti-Deficiency Act, only employees in "emergencies involving the safety of human life or the protection of property" can work during a shutdown.