The State of the Union address that President Obama delivered Tuesday was, in a sense, the first formal speech of his re-election campaign. It was his chance to wedge himself into the noise of the Republican primary campaign for 66 minutes of uninterrupted television time, and he took advantage of it.

It was a blue-collar speech, aimed largely at the swing voters Obama most needs to woo — middle- and low-income workers still struggling in the recession’s wake. His challenge was to convince them that, on economic policy, he is on their side.

To make his case, Obama even borrowed a few issues from the Republican candidates who have been excoriating him — an entire agenda of economic populism that had, until now, received relatively slight attention from the White House. He called for a new drive to attract manufacturing jobs back from overseas, a major plank of Rick Santorum’s campaign. He promised to get tough on unfair trade practices in China, a major plank of Mitt Romney’s campaign. And he called for much more domestic production of oil and gas, a favorite plank of every Republican’s campaign.

Until this year, when Obama talked about creating jobs, they were often “green jobs” — high-tech positions in the nascent alternative energy industry. But on Tuesday, the jobs the president talked about most were in one of the oldest manufacturing industries: automobiles. “On the day I took office, our auto industry was on the verge of collapse,” he said. “Some even said we should let it die. . . . Tonight, the American auto industry is back.”

That was a dig at Romney, who opposed the federal rescue of GM and Chrysler. (Although, to be fair, Romney was proposing bankruptcy, not death.)

On taxes, too, Obama made clear that he sides firmly with the regular folks. “You can call this class warfare all you want,” the president said. “But asking a billionaire to pay at least as much as his secretary in taxes? Most Americans would call that common sense.”

Obama said: “We don’t begrudge financial success in this country; we admire it. When Americans talk about folks like me paying my fair share of taxes, it’s not because they envy the rich; it’s because … somebody else has to make up the difference.”

That was a direct answer to Romney, who has accused Obama of practicing “the politics of envy” — or at least it was as direct an answer as possible in a speech pretending not to be a campaign address.

By sheer good luck, Obama spoke on the same day Romney belatedly released two years of tax returns, revealing that he paid only about 14 percent of his $21.6 million in income in federal taxes in 2010, a rate that is well below that of most middle-class families.

What connects Obama’s two points of greatest emphasis, manufacturing and tax rates? As campaign issues, they both play well among voters without a high-school education — the blue-collar voters Obama and other Democrats have struggled to attract.

Last year, two Democratic academics touched off a brief frenzy when they wrote an article arguing that, with white working-class voters shrinking as a percentage of the electorate, Obama could win reelection without them. But in the current climate, Obama sees an opportunity to win back the working class.

Romney, the GOP’s once and possibly future front-runner, appears to have a hard time appealing to low-income and even to middle-class voters; in South Carolina, the only income group he won was households making more than $200,000 a year.

It’s not clear that manufacturing can really be the main engine of an overall economic recovery; as Obama noted, manufacturing jobs have been declining for decades, and many of them will never come back. There may have been an element of economic nostalgia at work there — a yearning for the world of George Romney, not Mitt. But that was also part of the message: this isn’t Obama the Harvard elitist, interested only in new-age jobs, but a president who will gladly settle for dirt-under-the-fingernail jobs too.

If there was any doubt whether Obama intends to seek the votes of white blue-collar workers, his State of the Union speech put it to rest. He’s running against Mitt Romney already — on every front he can find.