A ban on military-style assault weapons in the United States is to lapse on Monday, prompting accusations that President Bush has deliberately sought not to have it renewed.
By Dan Griffiths
BBC correspondent in Washington
Assault weapons were banned in the Clinton years
The debate over the assault weapons ban goes to the heart of an issue that has divided America for decades. It also highlights the power of special interests at the centre of US politics.
The legislation prohibiting these military-style firearms was signed by President Clinton in 1994 - it outlawed 19 different types of gun.
But to get it passed through Congress he agreed to demands for a vote to be held ten years later to confirm the ban.
So the power to renew it lies with the politicians on Capitol Hill. Only they can introduce legislation to extend it.
Right to bear arms
Supporters of the ban, including gun control campaigners and police chiefs from some of America's largest cities, have been to Washington to press their case.
They claim that violent crime will rise without the ban in place.
Some Democratic politicians have blamed the Republicans - they control both Houses of Congress and have refused to schedule new legislation.
But it is not as simple as that.
The ban is opposed by a powerful interest group, the National Rifle Association.
It says it violates the second amendment to the US constitution, which it argues gives Americans the right to bear arms.
John Kerry backs gun rights but supports the ban
That is a controversial claim which is disputed by many.
But for the millions of gun owners in the US it is sacred ground.
This is just one of a number of social issues which split this country right down the middle.
Often known as America's "culture wars", they include such hot topics as gay marriage, the environment, and abortion.
And they can cut across political lines.
Gay marriage has supporters and opponents from both sides of the political divide.
Gun rights, while predominantly a Republican cause also has Democratic backers.
President Bush and John Kerry are both supporters.
The National Rifle Association has a strong network of vocal activists stretched right across the US.
They are very well organised and financed and that means they can have a big impact on Congressional races in certain districts.
So with all the seats in the House of Representatives and a third of the Senate up for re-election this autumn, for Republicans and Democrats a messy fight over gun control just is not worth the risk.
President Bush has said he would sign a new ban if one was passed, but with little political will in Congress that is unlikely.
His Democratic opponent, John Kerry, has talked tough about the assault weapons ban.
But it is hardly a main plank of his campaign.
And so that means that with gridlock in Congress and little enthusiasm from the presidential candidates, it is likely some of America's deadliest weapons may soon be back on the streets.