Liberal senator Marise Payne will quit federal politics by the end of the month, she has announced.

Senator Payne, a former foreign minister, confirmed the keenly anticipated decision in a lengthy statement to her Facebook page on Friday morning.

“It is an extraordinary honour to be elected to represent one’s community in the federal parliament,” she said.

“To have had the privilege to have served as long as I have, and in the process to have become Australia’s longest serving female senator in history, is something of which I am very proud.”

Senator Payne, who is considered a Liberal moderate, entered parliament in 1997.

She was foreign minister and minister for women under former prime minister Scott Morrison, and was also Australia’s first woman defence minister.

Most recently, under Opposition Leader Peter Dutton, she has been shadow cabinet secretary.

Senator Payne’s resignation follows the defeat at the NSW state election in March of her partner Stuart Ayres. He had been a minister in the Perrottet government.

Senator Payne said she was grateful for Mr Ayres’ support, which allowed her “to be a much-travelled cabinet minister for seven years.”

The battle to replace Senator Payne is expected to be fierce. Leading No campaigner and Indigenous leader Warren Mundine is considered the frontrunner.

The Nine newspapers report that Liberal power-brokers hope the one-time ALP president can unite the party’s conservative wing.

Mr Mundine ran for the Liberals in the lower house seat of Gilmore in the 2019 federal election, but was unsuccessful. He refused to rule out the possibility of seeking a Senate spot when contacted by the Nine papers earlier this week.

Former state minister Andrew Constance is also considered another likely contender. He unsuccessfully challenged for the seat left vacant by the death of Jim Molan earlier this year.

Opposition Senate Leader Simon Birmingham thanked Senator Payne for her contribution and service.

“Personally, I could not have asked for a better friend or more trustworthy confidante throughout my senate career,” he said.

“Again and again, Marise has shown her respect for the institution of the senate, the primacy of the parliament and the unique role of each parliamentarian.”

-with AAP