Trump's re-election is approaching the danger zone, polls show

3. In deep trouble: Jimmy Carter in 1980, George H.W. Bush in 1992

A profound rally-around-the-flag effect following the siege of the American embassy in Tehran had lifted Carter to new heights of popularity. But by this point in 1980, his numbers were falling fast.

With the hostage crisis dragging on and double-digit inflation strangling the economy, Carter fell to a 38 percent approval rating in June of ’80, falling behind Republican Ronald Reagan. Carter’s slide would only continue, with his approval falling into the low 30s in months ahead. On Election Day, he would carry just six states.

At this point in ’92, Bush was also watching his numbers drop, down to just 37 percent in an early June Gallup poll, a steep decline from his post-Gulf War high of nearly 90 percent the year before. The slumping economy was catching up with him, and his numbers would fall even further over the summer.

Bush hoped public unease with Democrat Bill Clinton would give him a chance to hang on, but Clinton pulled ahead after the July Democratic convention and never looked back. In a three-way race, Bush wound up winning just 38 percent of the vote — the worst for an incumbent in 80 years.