As Mitt Romney nears a running-mate decision, he may want to consider some unanticipated consequences of past selections.

He's said to be proceeding carefully to avoid following in the steps of Sen. John McCain, whose 2008 last-minute gamble on Alaska Gov. Sarah Palin went awry.

While Palin passed all the litmus tests of the party's right, her qualifications were widely questioned and she became the butt of late-night comedians.

In 1980, Ronald Reagan decided even later.

When a firestorm spread through the Detroit convention — and across news reports — that former President Gerald Ford was his choice, Reagan rushed to the hall to set things straight. His teammate would be George H.W. Bush. That worked out well: They won in November.

But four years earlier, Reagan was an early-decider. Too early.

Challenging President Ford, he announced Sen. Richard Schweiker of Pennsylvania as his running mate. Instead, Ford won the nomination narrowly and chose Sen. Bob Dole of Kansas. They lost to Democrats Jimmy Carter and Walter Mondale.

Bush's 1988 selection of Indiana Sen. Dan Quayle startled many Republicans. Complicating the roll out, Quayle got lost and had trouble getting through a surging New Orleans riverfront crowd to connect with Bush.

While the ticket won, Quayle was dogged by questions about his military service, debate performance and a golf trip to Florida with lobbyists.

George W. Bush put former Wyoming congressman Dick Cheney in charge of his search in 2000. Not finding anyone deemed qualified, Cheney got the job himself.

Texas businessman Ross Perot, waging a third-party challenge in 1992, selected Vietnam war hero Adm. James Stockdale. The tongue-tied Stockdale opened a vice presidential debate famously asking, "Who am I? Why am I here?"

Romney was heading late Friday for Norfolk, Va., to begin a bus tour of battleground states. President Barack Obama was hosting an annual dinner celebrating the Islamic holy month of Ramadan.