The US presidential election will not be free and fair, because millions of electors will either not be allowed to vote or will not have their votes properly counted. It could cost Barack Obama the White House, even if he wins most of the votes on November 4. This sensational claim is based on research by the New York Times (NYT) and BBC Newsnight. The NYT found that in some states for every new voter registered in the last couple of months, two voters have been removed – negating Obama's massive voter registration drive. This voter purging could mean fewer people voting next month than voted in 2004.

In Colorado, for example, which has seen a significant population increase since the last presidential election, the state has recorded a net loss of nearly 100,000 voters from its rolls since 2004. Louisiana, Michigan and Colorado are deleting registered voters from the rolls within 90 days of a federal election, which is illegal except when voters die, notify the authorities that they have moved out of state, or have been declared unfit to vote.

This widespread electoral malpractice is independently corroborated by a Newsnight investigation by Greg Palast. He reminds us that in the 2004 presidential election, between 1.6 and three million votes were cast but never counted, according to the US Election Assistance Commission. This is easily enough votes to have changed the outcome of the poll and put John Kerry in the White House.

Palast says that almost three million voters have already been purged from the voter rolls – mostly poor and black voters who are more likely to vote Democrat. During elections in New Mexico earlier this year, one in nine voters found that their names had disappeared from the voter rolls. In Colorado, the disenfranchisement is even greater, with 20% of voters being purged.

It has happened before. During the 2004 presidential election one in four registered Ohio voters turned up at the polling booth only to discover that their names were not on the voter roll, an exclusion rate of 25%.

Democrat leaders are too high on their "Yes we can" hype to kick up a fuss about this massive disenfranchisement of their voters. They naively assume that Obama's poll lead will give him victory, regardless of the election bias. It might. But then, again, it might not.

Another form of voter exclusion is happening in Michigan, where 62,000 lower income families, mostly Democrat supporters, face losing their homes to foreclosure. Loss of residence means losing their voting address and their right to vote. Many of the evictions are being orchestrated by a foreclosure company that supports the Republican party.

Michigan isn't alone. In several crucial swing states, including Nevada and Florida, foreclosures and the consequent loss of voting rights could affect the outcome and decide the presidency.

Election bias doesn't stop there. The Republican strategist

Karl Rove has backed a new law requiring voters to show photo ID at the polling booth. One in ten US citizens don't have photo ID. Among African Americans it is one in five. This requirement will disenfranchise millions of poor, elderly and black Americans, who tend to vote Democrat. In one swing state, Indiana, an estimated 100,000 African-Americans may lose their right to vote. A combination of voter roll purging and photo ID requirement could be enough to swing the presidential election in favour of John McCain – even if Barack Obama has a substantial opinion poll lead on election day.

Writing in Rolling Stone magazine in 2006, the civil rights lawyer Robert Kennedy Jr, JFK's nephew, revealed how voting irregularities in 2004 were enough to steal the presidency for the Republicans. He has also demonstrated that the electronic voting machines that will be used in the November 4 election are not reliable and accurate, and that they are vulnerable to hacking. Moreover, he shows that three of the four companies that supply voting machines and count the votes have close links with the Republican party.

Writing in the same magazine this month, Kennedy and Palast document large-scale election irregularities by the

Republicans that they believe could be enough to swing the election. Their meticulously researched expose and documentary catalogue evidence that the Republicans may have already stolen the 2008 presidential vote.

"If Democrats are to win the 2008 election," Kennedy and Palast conclude, "they must not simply beat John McCain at the polls – they must beat him by a margin that exceeds the level of GOP [Republican] vote tampering."