Reid, who has been the Democratic whip since 1998, announced Wednesday that he has the support needed to to lead his caucus.
Reid's path cleared Wednesday afternoon after Connecticut's Chris Dodd announced he would not seek the post when the Senate Democrats vote in December.
The outgoing and more liberal Durbin is believed to have the inside track as he would be a better match for Reid's relatively low-key personality and balance the incoming leader better politically.
Colleagues and political analysts told the Las Vegas Review-Journal that Reid was respected in Washington, but that his anti-abortion philosophy could be a handicap in such a high-profile, partisan job.
On the other hand, some observers told the newspaper Reid might help the Democrats reach out to voters in states outside the party strongholds in California and the Northeast.