WASHINGTON -- Hillary Clinton's campaign tried to move the Illinois presidential primary to a later date, saying a contest held after the Super Tuesday primaries might stop momentum for a moderate Republican candidate and emphasizing that Clinton and her husband "won't forget" a political favour, emails made public on Thursday show.

A November 2014 email hacked from the accounts of Clinton campaign chairman John Podesta was among nearly 2,000 new emails published by the anti-secrecy group WikiLeaks. The email, from Clinton's future campaign manager Robby Mook to Podesta, said Obama administration officials should use their connections in the president's home state to try to push back the March 15 Illinois primary by at least a month.

"The overall goal is to move the IL primary out of mid-March, where they are currently a lifeline to a moderate Republican candidate after the mostly southern Super Tuesday," Mook wrote. "IL was a key early win for (GOP presidential candidate Mitt) Romney" in 2012.

While the request would come from Obama, the president and former Illinois senator, "the key point is that this is not an Obama ask, but a Hillary ask," Mook said.

"The Clintons won't forget what their friends have done for them," he added. Clinton and her husband, former President Bill Clinton, famously gave special attention to allies considered "friends of Bill."

Clinton's campaign has said the FBI was investigating who hacked Podesta's email. Vice presidential candidate Tim Kaine told ABC's "The View" Thursday that the FBI and director of national intelligence have said "the Russian government is behind" the hack, adding that "anybody that would hack to try to destabilize an election, you can't automatically assume that everything in all of these documents are even real."

On the Illinois issue, Mook suggested that Bill Daley, a former White House chief of staff and longtime Illinois power broker, should reach out to Illinois House Speaker Michael Madigan to make the request.

Mook made it clear it would be a tough sell because Madigan and other Illinois Democrats "feel forgotten and neglected by POTUS," a reference to Obama.

Daley, whose father and brother were both Chicago mayors, told The Associated Press that he called Madigan as requested, but warned Clinton's team that moving the primary was unlikely because of a short time-frame.

"I made the call and talked to Mike and he listened and understood the reasoning," Daley said. "But my own judgment was the likelihood that either side would want a primary later in the legislative session was going to be slim to none."

The Illinois legislature moved up the 2008 primary to benefit its favourite son, then-Sen. Barack Obama, in his bid for the White House. The primary was held in early February that year to give Illinois more influence, but then moved back to its traditional date in mid-March.

This year the primary was held as scheduled on March 15. Clinton won the Democratic primary, while Donald Trump won the Republican contest.

Associated Press writers John O'Connor in Springfield, Illinois, and Mary Clare Jalonick in Washington contributed to this report.