Barack Obama's Endorsement Couldn't Come At A Better Time For Hillary Clinton

The president's approval rating is the highest it's been in years -- and that has implications for his successor.

In contrast to this year's historically unpopular presidential nominees, the sitting president is looking pretty good -- which could make a significant difference as the nation decides on his replacement.

Not all presidents choose to play an active role in electing a successor. But President Barack Obama, who endorsed Hillary Clinton on Thursday, is making his pitch at the height of his popularity in recent years.

HuffPost Pollster, which aggregates all publicly available polling, puts Obama's approval at a solid 50 percent, the highest it's been since the beginning of his second term.

"As Americans look to choose Obama's successor and decide whether they generally want to continue with the policy course he has set or change the nation's direction, the public will naturally reflect on how he has done as president," Gallup's Jeffrey M. Jones wrote in April.

Gallup's own tracking poll puts Obama's approval during the first four months of this year at 49.5 percent on average. That makes him roughly as popular as Ronald Reagan was at this point during his presidency and far more popular than George W. Bush, who largely laid low during the 2008 election.

Views of the president remain deeply polarized in a way that public opinion of many of his predecessors was not. Fewer than 15 percent of Republicans approve of his job performance, although that scant percentage still represents his best showing with the GOP since 2009. While independents' views of Obama have improved dramatically in the year, a majority of that segment still disapproves of how he's doing.

But the president is widely popular among Democrats. An average of 81 percent of Democrats approve of Obama, according to HuffPost Pollster. Most believe that both the economy and their own lives have improved since he was elected.

That popularity largely extends to Democratic supporters of Sen. Bernie Sanders (I-Vt.), whom Clinton now needs to win over to unify the party. In the most recent YouGov/Economist survey, 71 percent of Sanders supporters approved of Obama, although they were less enthusiastic in their approval.

Obama's ratings matters for another reason, too -- this early in a general election, an incumbent's approval is often a better predictor of the outcome than horserace polls.

"Elections are a choice but a lot of that choice is about whether or not people want to stay the course," political scientist Christopher Wlezien told Bloomberg in late May. "The referendum choice is going to be based a lot on what people think of the president and how the economy is doing."