One development in the 2008 presidential campaign which appears to have had longer legs to it than anyone expected was Mitt Romney’s practice of sending minions out to “dirty up” his primary rivals.

Several of Romney’s 2008 opponents complained of the attacks his camp unleashed on them, many with very little truth behind them.

Sound familiar at all?

One of the victims of the Romney dirt in 2008 was Fred Thompson, who at one time was considered a potential GOP savior in that cycle. Thompson’s campaign didn’t take off the way his supporters hoped; he seemed to lose interest in the fight once it got messy in the fall of 2007 and dropped out before primary season got too far along.

Thompson then endorsed John McCain despite a chasm of ideological difference between the two.

And now, he’s endorsing Newt Gingrich.

If Romney wants to win the GOP nomination, attacking his fellow Republicans isn’t the right way to do it. All that does is generate enemies who ultimately find a way to stick it in you.

Which Romney got a taste of today. Thompson’s endorsement might not tip the GOP race, but these things do add up.