The Act party will announce a new president in March to replace Catherine Judd who resigned last night.

Party leader Rodney Hide praised Ms Judd, saying she had been a fantastic president who had given him her full support.

He told NZPA Ms Judd had felt last year that she had held the position for long enough -- since 2001 -- but decided to stay on and see the party through last September's election.

"She kept me going through the campaign," said Mr Hide, who won the Epsom seat in Auckland from National against all the odds.

"She was a fantastic president. There was always media comment that somehow she wasn't supportive of me, that was never true."

Ms Judd said she had intended retiring after the election, and believed the right time had arrived.

"I've done four years and I stayed on an extra term to see the party through the election," she said.

"I think this is a fitting time to retire and someone else take over at this point in the party's career."

Ms Judd said she would continue to support Act, and help the party in any way she could.

"I'm very much committed to it, but I won't be taking on any formal role," she said.

Ms Judd became president in 2001 when she replaced the party's founder, Sir Roger Douglas. She was re-elected before last year's general election for a two-year term.

Under Act's rules the party president is elected through a postal ballot of party members. The result will be announced at the annual conference in March.

Mr Hide said nominations had already been called for, because the position was always contested and would have been this year whether or not Ms Judd had resigned.

Act had nine MPs in the last Parliament, but National's strong showing in last year's election reduced its caucus to two -- Mr Hide and Heather Roy.