The Tanaiste has called for support for the PDs as the only bulwark against a "tax-and-spend" Labour Party whose return to government, she says, could destroy Ireland's economic prosperity.
In a speech in Cork last night, Ms Harney signalled that her party will sell itself as the only alternative to Labour in the next general election campaign. The "clear choice" facing voters was which party to trust as a junior coalition partner, she said.
On the eve of what is almost certainly the last PD national conference before a general election, she concentrated almost exclusively on attacking Labour's recent proposal to spend an extra £3 billion over three years. This, she said, was "a blatant attempt to buy votes".
This policy could "blow" Ireland's economic success within 12 months, she warned. "A lurch to the left, whether with Labour or with other untried parties with untested policies" would risk "turning the clock back to the dismal days of the 1980s".
Ms Harney's speech will increase friction between the two parties, who spent much of the 1997 general election campaign attacking each other on ideological grounds.
She said the next election would produce a coalition government, and that the junior partner in that government would have a decisive influence over its policies.
Characterising Labour as a party of high spending and high taxes, she said hers was a party of "tax reform and tax reduction".
Ms Harney claimed credit for putting tax cuts, sound management of public finances and "pro-enterprise policies" on the agenda.
Labour had clearly not learned the lessons of the last 20 years, she said.
"Labour wants to take us back to borrowing. Labour wants to put a stop to tax reductions for working people. Labour wants to return to the tax-and-spend policies which brought this country to the brink of ruin in the 1980s."
She was critical of Labour's proposal to consider taking money from the pension reserve fund, set up to fund future pensions, to fund its spending programme.
"We believe also in making prudent provision for the future," she said. "We have set up a new pension fund, a national nest-egg that will enable us to look after the next generation of pensioners. Several billion pounds have been channelled into that fund and it will continue to grow in the years ahead."
Warning against complacency over the current economic prosperity, she said it had taken 12 years of hard work to create it. "The wrong decisions at the next election and we could blow it in 12 months.
"Let's not take risks with our prosperity. Let's not put everything that has been achieved on the line. Let's not turn the clock back to the dismal days of the 1980s."