WASHINGTON - US Senator John Kerry’s upcoming speech about national security at the Democratic National Convention in Charlotte, Carolina, could also be a secretary of state audition, diplomatic observers say. Kerry’s speech on Thursday night comes amid speculation that the Massachusetts senator is jockeying to succeed Hillary  - she has said she would step down if Obama wins re-election, The Hill reported Tuesday. While Kerry isn’t up for re-election until 2014, if Republicans gain control of the Senate in Nov, he would lose his the Senate Foreign Relations Committee chairmanship.

“I think giving him a slot says a lot,” one Democratic strategist close to Kerry told The Hill. “It sends a clear signal that he’s an important player.”

Kerry, who lost to George W. Bush in the 2004 presidential campaign, is scheduled to speak shortly before Obama accepts the Democratic presidential nomination.

Kerry and his staff have denied that the senator is eyeing Clinton’s job. Bill Danvers, the committee’s staff director, said he’s never seen Kerry exhibit interest in the secretary of state position when the two travel to global destinations.

“When we’re talking about what the committee agenda will be and what we’ll consider in terms of legislation, or hearings, or treaties, the issue of secretary of state just isn’t part of the conversation,” Danvers told The Hill. “That’s just not the way we do business.”