Obama’s power is waning and he faces an unprecedentedly partisan Congress. But there are still things he can do

Sometimes this President gives the impression of not being up for the fight

Tonight’s State of the Union address represents almost the last chance for Barack Obama to re-invigorate his gently subsiding presidency. Last time, with memories of a resounding election victory still fresh, great things seemed possible. But 2013 proved the most dismal of his five years in office; by the end of it, his approval rating had fallen to barely 40 per cent, amid growing evidence that voters no longer trusted him. This suggests he may be losing even the personal appeal that had been his strongest political asset.

Tonight Mr Obama will present his message live and unfiltered to tens of millions of Americans on primetime television. But this time his horizons, perforce, will be narrower, and the window of opportunity much shorter – probably no more than the six months until Congress’s summer recess, and the start of serious campaigning for the 2014 mid-terms in November. Should Republicans, as seems distinctly possible, add control of the Senate to that of the House, Mr Obama will truly be a lame duck.

But even for the next six months the going will be anything but easy. The opposition on Capitol Hill will be as intransigent as ever, and the chances of major legislative achievement are slim. The one exception is immigration reform, where Republicans – aware of their desperate need to attract more Hispanics – may perhaps be open to compromise. Otherwise, the days of bold and sweeping change are over, as even Mr Obama seems to acknowledge. “At the end of the day,” he said in a rather melancholy interview with The New Yorker magazine this month, “we [presidents] are part of a long-running story. We just try to get our paragraph right.”

But he can still put in a choice phrase or two. Sometimes this President gives the impression of being a fatalist, of not being up for the fight. Tonight, however, Mr Obama’s best bet is to be confrontational. A central theme of his address is likely to be the need to tackle America’s growing inequality – the gap between the very rich and the rest is wider now than at any time since the Great Crash of 1929 – and its corrosive social effects, coupled with a challenge to Republicans to work with him to do something about it.

Almost certainly, they won’t. White House aides have accordingly let it be known that Mr Obama will bypass Congress and rely, if necessary and wherever possible, on the executive powers of the presidency to achieve his goals, especially on issues such as the environment and climate change. To spell out as much tonight will not, of course, sit well with his immediate audience in the House chamber. But it will signal a leader determined to shape events during the three years that remain to him.

An uphill battle awaits, nonetheless. At this stage in the cycle, a president’s authority depends largely on his popularity. In Mr Obama’s case, this may be boosted by an improving economy and evidence that his healthcare reform, after last autumn’s shambolic start, is starting to deliver the goods. More likely, though, tonight’s speech will underscore a couple of core truths of modern American politics: that State of the Union addresses have a very short shelf-life – and that, in domestic politics at least, a president’s power is remarkably limited.