Illinois Senator Barack Obama on Tuesday won his ninth straight primary contest since the February 5 “Super Tuesday” primaries and caucuses, defeating New York Senator Hillary Clinton in Wisconsin’s primary election by a projected margin of 58 percent to 41 percent.

Obama’s victory was decisive. According to media reports Tuesday night based on exit polling, he won in every age group except senior citizens and won in every income bracket.

Repeating the pattern seen in last week’s “Potomac primaries”—Virginia, Maryland and Washington DC—the Illinois senator cut into constituencies previously claimed by the Clinton camp as the bedrock of their campaign. For example, he ran almost evenly with Clinton among women, while once again winning an overwhelming majority of votes cast by African Americans.

As in previous Democratic primaries, voter turnout reached record levels, with a particular influx of young voters. Exit polls in Wisconsin showed that 15 percent of those who went to the polls were first-time voters.

In the Wisconsin Democratic primary, all voters, regardless of party affiliation, were eligible to cast ballots. An estimated quarter of those voted in the Democratic contest were independents, who voted for Obama by a wide margin. Most Republicans who voted in the Democratic election similarly cast votes for Obama.

As of this writing, no results had been reported in the other Democratic contest Tuesday—the Hawaii caucuses. However, Obama, who lived in the 50th state for ten years, was expected to win that contest handily.

Wisconsin sends 74 delegates to the Democratic National Convention, to be held in Denver in August, while Hawaii sends 20. Going into Tuesday’s contests, Obama had a delegate lead over Clinton, including so-called “superdelegates”—party officials and functionaries who automatically serve as convention delegates—of 76, according to the Associated Press tally. The AP placed the delegate count at 1,294 for Obama to 1,218 for Clinton.

It takes 2,025 delegates to capture to party’s presidential nomination, but because the Democratic delegates are awarded on a proportional, rather than a winner-take-all basis, even were Obama to win all of the remaining primaries, he would not have a sufficient total to sew up the nomination.

However, the momentum of his campaign, and the clear signs that Clinton’s bid is foundering, will increase the pressure from top Democratic Party officials for Clinton to bow out of the race before the convention.

Clinton had all but conceded Wisconsin in the days following the Super Tuesday primaries, but after a shakeup in the top leadership of her campaign she changed course and made a bid to either win the state, or cut into Obama’s margin of victory sufficiently to claim that her campaign was on the upswing leading into the next contests, the March 4 primaries in Texas and Ohio. Going into Tuesday’s voting, opinion polls reported that she had reduced Obama’s lead in Wisconsin to 4 percentage points—a projection that was shattered by the actual results.

Now, the Ohio and Texas primaries—with a combined delegate trove of 370—loom as make or break contests for Clinton. Opinion polls had shown Clinton holding a clear lead in both states, but last night it was reported that new polls showed Obama pulling even in Texas.

In the run-up to the Wisconsin vote, both Obama and Clinton had stepped up their populist rhetoric, hoping to capitalize on the growing social anger over job losses, home foreclosures and general economic distress in a state that has been devastated by decades of plant closures and layoffs and is now feeling the added impact of a sharply slowing economy.

Both candidates had tacked toward economic protectionism, criticizing the NAFTA agreement and blaming it for the movement of jobs abroad. Obama, in particular, sought to use NAFTA against his opponent, reminding voters that the agreement had been signed by President Bill Clinton.

This turn toward economic populism has aroused growing concern among the corporate interests that are funding both campaigns. According to the Center for Responsive Politics, as of their last filings Clinton had raised over $115 million in campaign cash and Obama had raised over $102 million. The bulk of this money has come from wealthy donors and corporate interests.

Over the weekend, the Wall Street Journal published a lead article with the headline “Democrats’ Attacks on Business Heat Up,” and the Washington Post on Sunday published an editorial chastising Obama for his turn to “class warfare and populism.” On Tuesday, the lead campaign articles in both the New York Times and the Los Angeles Times focused on the same issue.

In substance, there is little difference between the economic proposals of the two candidates. Both are proposing the most modest of measures—a partial roll-back of Bush’s tax cuts for the wealthy, tax credits that would provide working families with several hundred dollars, a few billion dollars a year for infrastructure improvements—that would barely make a dent in the social crisis confronting millions of working class people, and do virtually nothing to address the huge and growing disparity in wealth and income between the financial elite and vast majority of Americans.

But the media, which has to this point given Obama, in particular, wide latitude in his demagogic appeal to mass discontent, is making it clear that even these minimal steps are beyond the pale.

At the same time, within substantial sections of the political and corporate elite, Obama’s candidacy is seen as an opportunity to effect a shift in foreign policy to bolster US imperialist interests threatened by the disastrous results of the policies of the Bush administration, particularly in the Middle East. His candidacy is also seen as a means of channeling growing social discontent and keeping it within the safe confines of the Democratic Party.

Speaking at a mass rally in Houston, attended by 20,000 people, Obama continued to adopt a “left” posture. For perhaps the first time in a stump speech, he denounced the Bush administration’s use of torture and declared that he would end the war in Iraq in 2009—a pledge that departs from his previous commitments to keep so-called “non-combat” troops in Iraq for an indefinite period and his repeated Senate votes approving war funding. This ratcheting up of antiwar rhetoric may be pitched toward what is increasingly shaping up as a general election contest between himself and Republican Senator John McCain, a diehard supporter of the war in Iraq and continued military threats against Iran.

McCain easily defeated former Arkansas governor Mike Huckabee in Wisconsin and in Washington state, which had only a Republican contest on Tuesday. McCain, who is now certain to win the Republican nomination, gave a speech in Ohio in which he declared himself to be the GOP candidate.

Significantly, he targeted Obama for attack, indicating that the Republicans now consider the Illinois senator their likely opponent. “I will fight every moment of every day in this campaign,” he said, “to make sure Americans are not deceived by an eloquent but empty call for change that promises no more than a holiday from history and a return to the false promises and failed policies of a tired philosophy that trusts in government more than people.”

Giving a preview of the fear-mongering and militarist thrust of the campaign he intends to wage, and all but accusing Obama of prostration before the “enemy,” McCain warned of “the confused leadership of an inexperienced candidate who once suggested invading our ally, Pakistan, and sitting down without preconditions or clear purpose with enemies [a reference to Iran] who support terrorists and are intent on destabilizing the world by acquiring nuclear weapons.”