A first-term President who's popular with the general voting public tends to get re-elected to a second term.
I mean, when you look back on the history of one-term Presidents, the consistent pattern between most of them is that they were unpopular, at least unpopular enough within their own party to be snubbed by the power-brokers in the backrooms when the next election rolled around.
John Adams? Wasn't as well-liked as Thomas Jefferson. John Quincy Adams? He actually lost the popular vote, but won in the runoff in the House of Representatives... essentially riling up Andrew Jackson and his supporters to turn out in droves the next election. Van Buren? First sitting President to suffer a major economic panic, so yeah pretty much unpopular. The Whigs are especially screwy one-termers: each Whig winner - Harrison and Taylor - DIED in office, leaving their unpopular Veeps - Tyler and Fillmore - serving out those terms. Both Franklin Pierce and James Buchanan were one-termers due to the ongoing slavery issue that made any Democrat sitting in the White House hugely unpopular in the North. Lincoln won re-election even in a divisive war because he stood on a more popular platform - Finish the War - than his opponent.
The next one-termer was Chester A. Arthur - fitting in for the assassinated James Garfield - who actually was well-liked (and not too bad a President) but wasn't the guy the party bosses wanted anymore. Grover Cleveland is an interesting case. He won the popular vote on his re-election effort but lost the Electoral vote, which almost makes his violate this hypothesis: except that he ran again and won a separate second term, the only President to do so. So he still fits.
Teddy Roosevelt really does prove my case (twice). Before him, Veeps who assumed the Presidency on the death of the President - poor McKinley, who was popular enough to win two terms - tended to be unpopular with either their party bosses or the electorate. Roosevelt became so popular with the voters - and so effective in shutting down his bosses - that he won his own term, the first to do so. The second time he proves my case is with Taft, his successor: not too happy with his administration, Roosevelt ran on a third ticket, effectively splitting the Republican vote... while Taft finished third.
Coolidge was popular enough to win his own term of office replacing Harding. Herbert Hoover was a one-termer for a very obvious reason: the Great Depression. FDR basically ran against Hoover three of the four times he ran for office, which should tell you how unpopular poor Herbert was. FDR's successor Truman ran a surprisingly effective campaign against an unpopular Congress and reticent Dewey, leading to the biggest electoral upset in American politics. When Truman's own popularity tanked during the Korean War, he quickly figured out he couldn't run for re-election and opted not to.
Eisenhower was the inverse of Hoover: incredibly well-liked, incredibly popular. Even having Nixon on his ticket didn't put a damper on things. Kennedy was more likeable than Nixon in 1960. Johnson was more likeable (believe it or not) than Goldwater and was running off of JFK's legacy. By 1968, Nixon was more likeable (I know, scary) than LBJ's replacement Humphrey (if the Dems stuck with Eugene McCarthy, they could have eked out a win) and Wallace. By 1972 it didn't matter who was running as the more popular candidate because Nixon's crew was sabotaging the Democratic primaries (hello, Watergate).
Carter was more likeable than Ford. Carter's unfavorables by 1980 hurt him compared to the well-liked Reagan. Reagan was still well-liked in 1984 when Mondale ran against him (which is one of the reasons Mondale only won Minnesota and DC in the Electoral votes). Bush the Elder's re-election efforts in 1992 were hurt by a hard recession, making him vulnerable to the smooth styling of Clinton (and Perot's third party vote losses). Bush the Lesser was still riding off of his huge popularity boost after 9/11 to eke out a win in 2004 over the stiff Kerry.
So where is this going?
Well, we're in a re-election year for Obama, coming off a rough first term. How do his re-election chances stack up?
Pretty good, actually. More people are hopeful about the economy now than they were in 2008. A current poll shows Obama with a 13 point lead over Romney, even as that poll shows Obama getting low marks for handling the economy. One thing to note in that article: Look at Romney's favorable-to-unfavorable numbers. Romney is 39 percent favorable to 48 percent UNfavorable. Being that un-liked a candidate bodes ill.
As long as Obama keeps his favorable numbers above Romney's, Obama has a good chance of winning re-election. Which is probably why we should expect a hurricane Category 5-level amount of mudslinging negative ads from now until DECEMBER 2016 for God's sake by the Republicans in order to drag Obama's favorables down.
So remember, Stay Sane and Vote Obama...