Heading into the Charlotte, N.C., convention, President Barack Obama was in trouble with independent voters. But instead of winning them back with appeals to national unity and promises of  compromise, he told them: You’ve got a stark choice – so choose.

He tossed them (us) a few rhetorical bones – a reference to the Simpson-Bowles debt commission he previously ignored, a bow to free enterprise as a jobs engine, acknowledgement that government can’t do everything and needs reform.

But basically, Obama’s acceptance speech was defiant, confrontational and contemptuous of Mitt Romney and Republicans, portraying them as heartless tools of millionaires, job-exporters, lobbyists, oil and insurance companies, toxic polluters, banks that break the rules –  and as enemies of old people, students, women and gays, to boot.

His message was: “forward” with me or “backward” with them. There was no softening of it: It’s war until Nov. 6 and, most likely, prolonged government gridlock after that.

Obama was characteristically eloquent, but this was no outreach speech – it was 95 percent base-mobilizing, with independents left to choose between “community” (directed and managed by government) and . George W. Bush.

Obama’s agenda for the future? He listed a set of worthy “goals” – a million new manufacturing jobs in four years, cutting oil imports in half, recruiting 100,000 math and science teachers, using defense savings to build infrastructure, $4 trillion in debt reduction – but without any description of how he’d achieve them.

Obama certainly provided more information about his direction than Romney did in just five paragraphs devoted to domestic policy in Tampa, Fla., but Obama said more about what he wouldn’t do than what he would do.

No new tax breaks for the highest earners: “I refuse to go along with that, and as long as I’m president, I never will.” Tax reform, yes, but “I refuse to ask middle-class families to give up their deductions for owning a home or raising their kids to pay for another millionaire’s tax cut. . I refuse to turn Medicare into a voucher” or turn Social Security “over to Wall Street.”

Whether the stark-choice approach works with independents will partly decide how this election turns out.

The Sept. 4 CNN-ORC poll indicated Romney had made considerable headway with independents. Sixty percent had a favorable opinion of him, to just 46 percent for Obama.

Fifty-seven percent said Romney would do a better job handling the economy, to 35 percent for Obama. The two were tied on foreign policy, and Romney led, 51 percent to 40 percent, on Medicare.

By 51 percent to 36 percent, independents thought Romney was the stronger leader; by 47 percent to 38 percent, that he was more optimistic about the country’s future; and the two were tied on who was more in touch with the problems of the middle class.

In 2008, Obama carried independents 52 percent to 44 percent over Sen. John McCain (R-Ariz.). Last week, the CNN poll had Romney up, 52 percent to 42 percent.

In Charlotte, Obama’s team sent out its most popular figures to repair the damage – his wife, Michelle, and President Bill Clinton, famous for turning centrist after Republican victories in 1994 and for making deals with Republicans despite their impeaching him.

The job Michelle Obama and Clinton did – and Vice President Joseph Biden and keynote speaker Julian Castro, too – was to recount Obama’s accomplishments, including saving America from a Great Depression, adding 4.5 million private-sector jobs since 2010, passing a health care overhaul, saving the auto industry, killing Osama bin Laden, etc.

This was not just to counter GOP charges that Obama has kept no promises but to make voters feel better about the track the country’s on – currently they’re 63 percent negative.

Obama and others acknowledged that the economy still faces a long slog back, but Clinton had the best single line of the convention: “In Tampa, the Republican argument against the president’s re-election was pretty simple: We left him a total mess, he hasn’t cleaned it up fast enough, so fire him and put us back in.”

Clinton, with his credibility as a centrist and job-creator, declared that no president in history could have repaired the economy in four years.

And he claimed that Obama tried to reach out to Republicans and “is still committed to cooperation” but has been rebuffed by “the faction that now dominates the Republican Party,” which thinks “government is the enemy and compromise is weakness.”

Indeed, such a faction does exist, but Romney and his running mate, Rep. Paul Ryan (Wis.), aren’t part of it.

Moreover, as the history of the polarized past four years is written (Bob Woodward has just added to it), Obama comes off at least as culpable as Republicans.

Obama’s record is that he ran as a  “post-partisan” unifier in 2008, then governed as a big-government liberal when he had huge Democratic majorities for two years. When voters rebuffed him in 2010, he did not “do a Clinton” and deal. He decided he’d do what he could by executive order and take the rest to the voters.

And now he has. “This is what the election comes down to. Over and over, we have been told by our opponents that bigger tax cuts and fewer regulations are the only way; that since government can’t do everything, it should do nothing.

“If you can’t afford health insurance, don’t get sick. If a company releases toxic pollution into the air your children breathe, well that’s the price of progress. If you can’t afford to start a business or go to college, take my opponent’s advice and ‘borrow money from your parents.'”

It was all red meat for the Democratic base, scraps for independents and straw men for all. (Has any Republican suggested that the government “should do nothing?”)

Base-mobilization and vilification may win the election for Obama, especially if middle-class voters think they will be better off with government help than with small-business growth.

However, the bitterness of 2012 does not bode well for problem-solving in 2013.  Obama will not have an all-Democratic Congress, and Republicans have no reason to trust him.