Since it became obvious in early March that Mitt Romney would be the Republican nominee, conventional wisdom had it that: 1) Romney was a weak candidate; 2) the Republicans would have a base problem; and 3) President Obama surely would win.

Over time the first two prongs of conventional wisdom melted away. Romney delivered thoughtful speeches (at Liberty University, in Iowa), showed readiness to duke it out (on Bain Capital) and displayed deft aggressiveness (going to Solyndra). With his increasing proficiency and a series of self-inflicted wounds by the president (e.g., “Life of Perpetually Dependent Julia”), the conservative base warmed to Romney. The more negative and caustic the president became, the more Romney seemed to radiate Reagan-like cheery calmness.

And yet the chattering class seemed comfy in the certainty that the economy was good enough and Obama’s favorability advantage big enough to insure his re-election.

Once again these assumptions crumbled in the course of just a few weeks. Romney has largely made up the favorability gap. And then the economic shoe dropped when jobless and growth numbers went from mediocre to rotten.

The Post’s Dan Balz reported:

[May’s] dismal jobs report and some unexpected words from Bill Clinton delivered a bracing reminder to President Obama and his advisers that the election remains primarily a referendum on his record and that their path to victory may lie less in trying to discredit Republican Mitt Romney and more in winning a battle of ideas with their Republican rival.

The latest report — just 69,000 jobs were added last month — was far worse than forecasters had predicted and undermined the administration’s contention that the economy is truly on a path to recovery. Administration officials pointed out that the economy added jobs for the 27th consecutive month. The weakness of that response underscored the challenge facing the president as he seeks to convince voters that he has the tools and the political wherewithal to fix what still ails the economy.

The New York Times fretted in an awkwardly constructed headline: “Weak Economy Points to Obama’s Constraints.” Translation: Obama’s lousy performance on the economy is a big problem for him. Or, as the Times would have it, the poor dear is at the “mercy of actors in Europe, China and Congress whose political interests often conflict with his own.” There is no shortage of excuses, you know.

Whatever you think is the cause of the economic doldrums, it has now dawned on the Democrats and the press that Obama could lose this thing. And, indeed, the economy might just get worse given that Obama refuses to deal with the “fiscal cliff.” Heck, it’s not 1996 any more, confesses the Times:

Continued economic anemia plays to Mr. Romney’s call for new stewardship, and to Republicans’ demands to extend and deepen the Bush-era tax cuts for the wealthiest Americans rather than let them expire, as Mr. Obama and Democrats want. And they figure that if Mr. Romney succeeds, it will probably help them win close House and Senate races, while Mr. Obama’s re-election could do the opposite.

By emboldening Republicans, the report on Friday that the economy added only 69,000 jobs in May seemed to dash the hopes of some in the White House for a replay of 1996. That summer, as President Bill Clinton sought re-election with the economy improving, Republicans in Congress decided that their party’s weak presidential nominee, Senator Bob Dole, was doomed.

In reality, Romney was never as poor a candidate as the left dreamed and the grouchy right wing feared. And Obama’s poor economic results were always going to be a problem. But May’s especially poor economic figures acted as a rude wake-up call, shattering the confidence that Obama would not just win, but win with some ease.

With the collapsing economy other Obama stratagems also become problematic. Is railing at the profit motive so smart right now? Will the public be distracted by ploys like tying Romney to Donald Trump or a concocted “war on women”? All of that seems counterproductive and decidedly unserious.

Consider also the tactical assumptions that have collapsed. Obama once was thought to have North Carolina in his column. But now that’s a long shot. Then the Obama team said the president would win every state Sen. John Kerry (D-Mass.) carried in 2004. But now at least two of the states that Kerry carried are toss-ups (Wisconsin, New Hampshire). Obama’s team convinced itself Arizona would be in play; That is now regarded as a pipe dream.

We still have five months to go to election day. Romney may make mistakes or stumble in the debates. Promising economic signals may be spotted. International events may work to Obama’s advantage (e.g. support for Israel in the event of a strike against Iran). But if you’re a betting person it might be smart to put some chips down on Romney; he’s a steal on Intrade right now.