A deal by US lawmakers to raise the country's debt ceiling passed its first hurdle last night but failed to lift shares after dreadful manufacturing data.
The IMF has said Britain's economy has less capacity to grow quickly over the next few years than the government had hoped, raising the spectre of more tax rises and spending cuts to keep Britain's recovery on track.
US markets have reversed earlier gains after manufacturing data raised further doubts about the strength of the economic recovery.
Global markets climbed overnight and in early trading on Monday on news the US has agreed an outline solution to its debt crisis.
The UK economy will only grow at a "sluggish" rate this year, according to the CBI.
President Barack Obama has announced a deal to end the US debt crisis, which will raise the nation's debt ceiling by at least $2.1trn and cut the federal deficit by as much as $2.5trn over a decade.
A chorus of global banks has warned that Washington risks triggering a global slump and may suffer permanent loss of credibility by flirting with default on America's $14.3trn (£8.8trn) federal debt.
A vote on a Republican bill to raise the US's debt ceiling and prevent it from defaulting for the first time has been delayed.
US and Asian markets fell overnight on fears the US government will fail to resolve its debt crisis, ahead of a crucial vote by the House of Representatives today.
Boris Johnson has called on the Chancellor to cut National Insurance (NI) and scrap the 50p higher income tax rate.