Donald Trump
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A spate of new surveys show a sizeable post-convention bounce for GOP presidential candidate Donald Trump – including at least one that puts Trump ahead of Democratic candidate Hillary Clinton as she heads into the Democratic convention this week. A new CNN poll, for example, finds Trump now leading Clinton 44% to 39%, while a Morning Consult survey shows Trump now leading Clinton 44% to 40%.

Should Democrats panic?

In truth, post-convention bounces seem to bear little relation to what happens at the polls in November. The following chart, put together by the American Presidency Project at the University of California-Santa Barbara, shows the post-convention impact for candidates from 1964 to 2012.

Among other things, it shows a number of presidential candidates who enjoyed a big post-convention bounce (or at least one bigger than their opponents) who went on to lose the election. Those candidates include Barry Goldwater, who saw a bigger post-convention bump in 1964 than Lyndon Johnson; both Jimmy Carter and Walter Mondale against Ronald Reagan in 1980 and in 1984; Michael Dukakis versus George Bush; and John McCain over Barack Obama.

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On the other hand, in 1992, Bill Clinton enjoyed a 16-point bounce in 1992, versus a 5-point bump for opponent George H.W. Bush, and went on to win the White House. Also interestingly, the post-convention bumps for Al Gore and George W. Bush in 2000 were exactly the same – 8-points – which turned out to be a harbinger for the closeness of that contest.

Bottom line: It’s far too soon for triumphalism from Trump’s supporters, and it’s also too soon for Clinton proponents to worry.

This post has been updated.