Mary Harney's contribution to the social and political transformation of this country earns her a prominent place in the history books. The praise for her straightforward, no-nonsense, liberal, can-do agenda is welldeserved. Many (including a lot of Fianna Fail supporters) will argue against her party's right-of-centre economic agenda and her predilection for private enterprise to provide where the state falls lamentably short, but her impact in terms of busting apart the old, corrupt order that was Fianna Fail under Charles Haughey, must be recognised.

Her leadership and influence have resulted in greater openness and accountability in the decision-making and political process.

She made mistakes, but the heavy hand of the Haughey era was lifted by people like Harney who didn't just oppose, but were determined to bring change from within the cabinet room.

But pragmatic and successful as she was within Leinster House, her wider appeal has been falling. For Harney, the exit sign has been flashing for some time now. As today's Sunday Tribune/Millward Brown IMS poll shows, her popularity until her resignation as leader continued to decline. Support for her party generally, though steady at 4%, languishes down at the "margins of error" in sampling terms. It is possible that every single PD TD could lose his or her seat.

But her resignation has changed everything. Harney was the rope keeping the wriggling bag of egos that is the PDs firmly tied and, thanks to her friendship and trust with Bertie Ahern, the fixative that bridged any gaps between the backbenchers of Fianna Fail and PD policy.

For Mary Harney, now is definitely the right time to go. Her spell as health minister has failed in its aim of resurrecting her popularity, and that of her party, as the ministerial ministering angel who worked miracles where others failed. It has left the PDs, who can claim success for their economic vision, open to attack on their ability to guide reform in the social sphere.

Candidates for the leadership must declare by tomorrow at noon. But if the party is to survive the coming general election, Michael McDowell can be their only choice of leader.

The general election campaign was officially launched last week by Bertie Ahern on his Wesport walkabout. McDowell is the PDs' most important member by a long shot. He has already threatened to leave the party if Mary Harney did not stand down to let him bid for the leadership. If the party votes for anyone else, their most important electoral asset will walk. His "be radical or be redundant" political philosophy may be the last chance for the PDs.

Certainly, today's poll shows that voter attitudes towards one of McDowell's main political reforms as justice minister, the tough new immigration bill, are far more in tune with his hardline views than those of the more liberal Liz O'Donnell.

But McDowell, as leader, as he seems certain to be declared tomorrow, must tread carefully. Become too radical and he may alienate voters who are already deserting the PD call. Play it too safe and he won't attract the swing voters he needs.

McDowell has the power to either attract or alienate in huge numbers. He has eight short months to perfect his pitch. If he gets it wrong, he may find that Mary Harney jumped just in time, her political legacy all that is left of the sinking PD ship.