What a difference 12 hours makes.

There was Andrea Horwath, jubilant on Thursday night after the NDP win in the Niagara Falls byelection, clearly outlining the party’s election platform.

The party will cap CEO salaries in the public sector, declared a feisty Horwath, as she went on to enunciate a laundry list of other pledges — tax credits for companies that hire young people as well as vague promises to make life more “affordable” for the average family.

It was a rallying cry that sent a message to the other two parties: We’re ready to fight an election.

Barely 12 hours later, when the cheers in Niagara Falls had subsided and the cold light of a February day had dawned, Horwath returned to Queen’s Park in a far more subdued fashion.

Gone was the call to arms.

She was back to the old Andrea — the let’s-make-a-deal leader, who’s once again prepared to wheel and deal and blackmail the Liberal government of Premier Kathleen Wynne in order to give support in the spring budget.

“We’re going to be focused not on election fever like the other two,” Horwath told a news conference Friday.

“That’s the message from last night,” she said. Which actually wasn’t the message she’d given the night before.

“The other two leaders might talk about elections all the time and whether or not they want an election or they don’t. What I’m going to talk about are the priorities of Ontarians,” she said.

Well, if I had a political weathervane, I’d say she went from scorching hot and rarin’ to go to a frosty “not-so-fast” Ice Maiden — all within half a day.

In her concession speech at the party for Liberal candidate Sandra Yeung Racco, Wynne also appeared to be rallying the troops. At one point, she actually talked about “heading into an election.”

As the legislature returns Tuesday after its Christmas Break, all eyes will be on Wynne and Horwath.

It’s unbelievable that Horwath would support yet another Liberal budget. The longer she props up the scandal-plagued Wynne government, the less credibility she has.

How can you complain about deleted e-mails or squandered money — and then vote to keep that government afloat?

Horwath is walking into the trap many deal-makers set when they keep an unpopular minority government afloat: they get power hungry — willing to give up their core principles in order to support a corrupt government and cling to power.

The NDP’s Wayne Gates, the union activist who won the Niagara Falls beyelection, could end up as a footnote of history — one of the shortest serving MPPs ever.

Two things could happen: Horwath could bring down the government over the budget. Or Wynne could go to Lt.-Gov. David Onley and ask him to dissolve Parliament, triggering an election.

If that happens within the next couple of months, it would be tough for the NDP to hang on to Niagara Falls.

Unions threw massive support into the riding and boasted about having 1,000 volunteers there during the campaign.

Yet, Gates squeaked by Tory candidate Bart Maves by less than 1,000 votes. In a general election, that union support would be spread over 107 ridings — and Gates might not get re-elected.

On Friday, PC leader Tim Hudak came out swinging also, pointing to the massive resources unions had mustered there.

“Give me a level playing field in Niagara Falls and I win that seat. It’s a PC seat,” he told reporters.

And he launched an offensive against the Working Families Coalition and its head, Patrick Dillon, who has targeted every Tory leader since Ernie Eves with millions of dollars in negative advertising.

“The reason that big labour has come together is because they want to run the show,” Hudak told reporters.

“By influencing elections like Niagara Falls, they’ve got another MPP in their pocket.

“They don’t care if it’s NDP or Liberal, it’s basically the same thing. If Sid Ryan or Pat Dillon says ‘Jump,’ they say ‘How high?’”

Surprisingly, there are still pockets of strength for Wynne and the Liberals — especially in Toronto, where the ongoing antics of Mayor Rob Ford have overshadowed the litany of Liberal scandals, such as gas plants, Ornge and deleted e-mails.

The longer Horwath stays in lockstep with the Liberals, the more she risks voters forgetting the lies and cover-ups.

Will she continue her crazy mambo with the Liberals?

Or is she ready to rumble?