Michelle Obama casts her vote for US prez poll

United States First Lady Michelle Obama has already cast her vote for the November 6 presidential election, using the "early voting" provisions of the country's electoral process.

"What a great Monday – this morning I voted for @BarackObama," Michelle tweeted on Monday night, hours after her twitter handle announced that the First Lady had cast her 2012 ballot.

US President Barack Obama re-tweeted saying he would soon follow suit.

"I'm following @MichelleObama's example and voting early, on October 25," said the US President.

If that happens, it will be the first time that a presidential candidate will not vote on the election day.

The tweets from the US President and the First Lady came as news reports suggested that Obama was leading in early voting.

Meanwhile, the Romney campaign challenged the poll results of early voting, in which Obama is leading.

"Yesterday morning, a poll was released that claimed President Obama has a big advantage over Governor Romney among those who have already voted. This claim can easily be proved flawed and untrue," the Romney campaign said in a memo released on Monday.