President Barack Obama may make a few headlines in his re-election year State of the Union address; in a similar setting, Bill Clinton declared the “era of big government is over,” while George W. Bush suggested he had tamed Libya’s Muammar Qaddafi.

Other than setting parameters for the national elections, Obama’s speech tomorrow night before a joint session of Congress is likely to prove as ephemeral as those of these predecessors.

Over the next few weeks, much attention will be paid to Congress reconvening, the president’s speech, and the administration’s budget. Yet the presidential contest more likely will be shaped by subsequent and uncertain events affecting the economy, national security and politics.

Predictably, the first is the economy. The White House nervously looks across the Atlantic, hoping the European Central Bank’s actions have calmed the financial crisis, though it probably is unsettled by ECB President Mario Draghi’s comment last week that the situation remains “grave.”

A deterioration of the European crisis would affect the U.S. economy, hurting business and consumer confidence. That could make for a toxic climate for Obama’s re-election effort.

The president is counting on the economic forecasters being wrong. One of the best, Goldman Sachs Group Inc., citing continued household deleveraging and fiscal drags from cutbacks in state and local spending, predicted a sluggish 2012, with unemployment rising to 9 percent.

Understating Growth

The consensus forecasts for growth in 2011 were too high by about 1 percentage point; this time, Democrats hope it goes the other way, that the consensus understates growth, which could put the jobless rate at close to 8 percent in October, a good number for the president.

More sobering is the concern in Obama’s national security circles over the possibility of war or a terrorist incident. The most often-cited fear is that Israel tries to take out Iranian nuclear facilities. That, top intelligence analysts say, would result in retaliation against U.S. targets by Iran and its proxies, including Hezbollah. The Fifth Fleet is in Bahrain, and there are other bases in the region. Further, Iranian proxies have surfaced not only in the Middle East and Africa but in Thailand and South America.

If oil shipments in the Strait of Hormuz are impeded, oil and gasoline prices could spike just in time for the election. The Iranians don’t even have to close the passage; they could simply mine it, forcing Lloyd’s of London to jack up insurance rates, which would certainly lead to higher prices at the pump.

There’s almost no terrorist expert who dismisses the prospect of another attempt or attack on America, though many think it wouldn’t be as likely to succeed as in the past.

The timing of war or any possible act of terrorism would have political implications. If it occurred right before an election, a rally around the flag mindset might help the incumbent. If it occurred much sooner than that, the political fallout might be severe.

If war or any major terrorist act is avoided, it’s going to be tough for opponents to depict Obama as weak; after all, Osama bin Laden and Qaddafi were dispatched on his watch.

In any case, the political landscape will look different in October than it does now.

An important element will be how the Republican presidential contest evolves. If Mitt Romney wins big in the Jan. 31 Florida primary, he goes back to being the almost certain nominee.

South Carolina

Yet former House Speaker Newt Gingrich’s big victory in South Carolina this weekend makes a protracted struggle more likely. Every time attention focuses on Gingrich, there is scrutiny of his political and personal baggage, which includes two messy divorces, an affair during the time he was speaker, ethical transgressions and special pleading for interests such as Freddie Mac that are anathema to most Republicans.

Even before South Carolina, Romney had a rocky two weeks, mishandling the controversy over his record as a private-equity mogul, equivocating about releasing his tax returns after acknowledging that he paid taxes at a lower rate than many far-less wealthy Americans.

There are two possible theories, detached Republican professionals say, drawing on baseball analogies: This is Romney’s equivalent of spring training or exhibition season, toughening him to handle the rigors of the general election. Or he is a great minor league player who’s not up to the challenges of the political majors.

If Romney wins the nomination, still a high probability, the candidate’s relations with the movement conservatives will help shape his political persona for the fall. Currently, there is much mistrust between the one-time moderate Republican governor of Massachusetts and his party’s right wing.

It’s important for him that these fissures heal; he needs an energized base in the general election.

For months, Republicans have been proclaiming how motivated their voters are. Yet the turnouts in the first voting states of Iowa and New Hampshire were disappointing, well below the surge that exuberant Democrats experienced in those contests four years ago.

If, on the other hand, some of the more conservative Republican elements try to make the nominee heel to a litany of demands, he’ll look weak and be forced to embrace unpopular general-election positions.

It’s also probable that there will be at least one, and perhaps multiple, third- or fourth-party or independent candidacies in the fall. These probably won’t be figures that can break into the double digits, though the votes they siphon off can affect a close election. Who these also-rans might be and whose votes they will drain remains uncertain.

Just think of the changes over the past nine days: Two candidates dropped out, and the front-runner, Romney, stumbled, as it turns out he didn’t win the Iowa caucuses after all. Meanwhile, one of Gingrich’s ex-wives said he had asked her for an “open marriage,” a disclosure he used as an opportunity to excoriate the news media. Imagine what might unfold over the next nine months.

(Albert R. Hunt is the executive editor for Washington at Bloomberg News. The opinions expressed are his own.)

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To contact the writer of this column: Albert Hunt in Washington at ahunt1@bloomberg.net

To contact the editor responsible for this story: Max Berley at mberley@bloomberg.net.