In brief remarks a few moments ago, President Obama sought to lay down a very clear marker on taxes, telling Republicans that he would not accept any approach to deficit reduction that doesn’t include a greater sacrifice from the wealthy. Obama claimed the election had made the will of the people clear, and demanded Congress honor it — exactly what the left and Dems had hoped to hear.

In another move that will intensify the brinksmanship, I’m told labor unions are preparing a multi-million campaign, including TV ads, to pressure Congress — Dems included, if necessary — to stick to the core principles Obama laid down when the fiscal cliff talks heat up.

“If we’re serious about reducing the deficit, we have to combine spending cuts with revenue — and that means asking the wealthiest Americans to pay a little more in taxes,” Obama said. “I refuse to accept any approach that isn’t balanced.”

Obama also called on Congress to “extend the middle-class tax cuts right now.” The Senate has already passed a bill that would extend just the middle class cuts. This represents Obama pressuring the GOP-controlled House to pass that same bill right away. Obama cited the election results in calling for action.

Conservatives such as Grover Norquist are already pressuring Republicans to stand firm against tax hikes for the rich. So the question now is what kind of pressure the left will mount to ensure the fiscal cliff talks adhere to the principles Obama laid out.

Along those lines, I’m told that SEIU, AFSCME, and the National Education Association are putting together a major push, including TV ads, to pressure Congress to adopt a fiscal cliff approach that doesn’t do any harm to Medicare, Medicaid, and Social Security — and includes higher taxes from the wealthy. If necessary, the campaign might target Dems who stray from these principles.

“We believe this election was a crystal clear expression by working people in this country that the rich need to pay their fair share,” SEIU president Mary Kay Henry told me in an interview. “The new majority needs to continue to hold everyone accountable — Democrats and Republicans — by making sure we back the president’s vision for the country.”

Liberals are sure to be cheered by Obama’s remarks today. He led with an argument about tax fairness, and made a moral case for an economic blueprint that places some of the burden of deficit reduction on the wealthy, so seniors and middle class families don’t end up doing all the sacrificing. He noted that the will of the people, as expressed on Tuesday, had backed him up — and told members of Congress it’s time they get in line with the will of the people, too.