By Justin Webb BBC News, Washington

President Bush thinks Mr Bolton will "get the job done"

The failure leaves open the possibility Mr Bush will appoint Mr Bolton without Senate approval during a recess.

There are 100 senators and 55 of them are Republicans, so a straightforward vote on John Bolton would almost certainly result in his confirmation.

But 60 members are needed to override a delaying filibuster in the Senate.

So, provided the Democrats remain united, Mr Bolton will not be passed.

'Unreasonable'

The Democrats say they are not blocking the nominee completely.

They would allow a vote if further information were given on his behaviour while he worked at the state department.

But the Bush administration says that demand is unreasonable.

The two sides are deadlocked.

Assuming Mr Bolton does not withdraw, the president is faced with a tough political choice.

He has the power to appoint his man over the heads of the senators during their recess for the 4 July holiday - an appointment which would last until 2007.

Would that look like a bold move overcoming petty partisan politics, or the desperate strategy of a lame-duck second-term president?