President Obama has “the worst ratings of any president at the end of his first year.”

It’s no secret that President Barack Obama has had a rough first year in office. His approval ratings in the major polls hover just below 50 percent — a decline from earlier levels that has cheered Republicans and conservative commentators.

In a Dec. 16, 2009, Wall Street Journal column, Karl Rove — the mastermind of George W. Bush’s two election victories — riffed off the grade of a “solid B+” that Obama gave himself in a Dec. 13 interview with Oprah Winfrey.

In a column headlined, “The President Is No B+,” Rove wrote that “Barack Obama has won a place in history with the worst ratings of any president at the end of his first year: 49 percent approve and 46 percent disapprove of his job performance in the latest USA Today/Gallup Poll.”

We’ll begin by clarifying a few points.

First, we should note that Rove was guilty of rhetorical excess when he said that Obama’s numbers are the worst of “any president” at this point. Gallup’s historical data — the longest-running of the major polling firms — dates back to Harry Truman, who was the first president whose entire tenure was polled in a fashion that modern experts would consider scientific. So Rove should have argued that Obama’s numbers were the worst of any post-World War II president at this point in his term.

Second, Rove misspoke when he referred to measuring Obama’s ratings at the end of his first year. By definition, those numbers won’t be available until late January. But in assessing his statement, we’ve sidestepped that problem by asking Gallup to provide us the approval ratings for December of the first year in office of the postwar presidents, so that the ratings for each can be compared more directly with the figures we have for Obama.

Third, not all postwar presidents came to office equally. Dwight Eisenhower, John Kennedy, Richard Nixon, Jimmy Carter, Ronald Reagan, both Bushes and Bill Clinton were all elected, so their presidencies all started at the usual time of the year. By contrast, Truman, Lyndon Johnson and Gerald Ford assumed office after the death or resignation of their predecessor. Johnson’s approval ratings roughly a year after taking office were around 70 percent, while Truman and Ford were both around 40 percent at that point in their tenure — a level lower than Obama’s today. But because the comparison isn’t exact, independent analysts advised us to exclude Truman, Johnson and Ford from our analysis.

So, here are Gallup’s December approval and disapproval ratings for all elected presidents since World War II. (For Clinton and George W. Bush, Gallup polled on presidential approval twice a month rather than once a month as previously, so the numbers below reflect an average of the two December scores for those presidents.)

• Eisenhower, 69-22
• Kennedy, 77-11
• Nixon, 59-23
• Carter, 57-27
• Reagan, 49-41
• George H.W. Bush, 71-20
• Clinton, 53-39
• George W. Bush, 86-11
• Obama, 49-46

Compared to these predecessors, Obama’s numbers are indeed the weakest — but he’s tied with Reagan in that unflattering achievement.

The similarities between the approval-rating paths of Obama and Reagan are actually quite striking, wrote Charles Franklin, a University of Wisconsin political scientist, in a recent post at the Web site Pollster.com. “Both replaced deeply unpopular predecessors,” Franklin wrote. “Both enjoyed significant gains for their party in both houses of Congress. Both faced ‘worst since the Depression’ economic circumstances. And each in his own very different ways attempted to reshape government in the early months in office.”

It’s worth adding a few words of caution about this kind of comparison. Ratings after one year don’t necessarily correlate with ratings throughout one’s term. For instance, in December 2001, George W. Bush’s 86 percent approval rating was largely due to a wave of support after the 9/11 terrorist attacks. Bush wound up his second term in the low 30s.

Still, if you’re making the comparison — and political observers have been doing precisely these sorts of comparisons for years — Rove’s statement holds up fairly well. Yes, Rove spoke too loosely when he said that Obama’s numbers were the worst of any president’s, and he failed to mention equally bad ratings for Reagan, a conservative icon whose politics were more in tune with Rove’s than Obama. But with the exception of Reagan, every other elected president had clearly higher approval ratings at this point in his tenure than Obama has. So we rate Rove’s statement Mostly True.