Speaker of the House Paul Ryan endorsed Donald Trump, but...

Speaker of the House Paul Ryan endorsed Donald Trump, but Dan Janison wonders if endorsements carry much weight with voters. Tuesday, June 7, 2016 Credit: Getty Images / Mark Wilson

Most endorsements bring a campaign little if any tangible benefit. But Republican nominee-in-waiting Donald Trump especially might find a number of the supportive statements he received from GOPers to be fairly useless.

House Speaker Paul Ryan let it be known last week, through an op-ed piece in The Janesville Gazette of Wisconsin, that he would vote for Trump. But this week, Ryan called the billionaire’s attack on a federal judge “the textbook definition of a racist comment.”

With backers like these . . .

Sen. John McCain (R-Ariz.) — even after enduring Trump’s snide remarks about his having been a POW — said: “You have to listen to people who have chosen the nominee of our Republican Party.”

How McCain’s minimal endorsement boosts either man on the November ballot is hard to see. His simple tip of the hat to Trump’s sweep in the primaries might only remind people of the nasty put-down.

For that matter, it is difficult to believe California Gov. Jerry Brown’s endorsement of Hillary Clinton helped her in Tuesday’s primary there. It does make it look like Brown thought she would win.

Maybe it was worth something to Democrats that Brown expressed urgency about beating Trump.

But that won’t erase YouTube videos from 1992 of Brown accusing Democratic primary rival Bill Clinton of “funneling money to his wife’s law firm for state business,” Or in the same exchange, the future president doing his famous finger wag as he told Brown: “You’re not worth being on the same platform as my wife.”

And an endorsement's value doesn’t seem to grow when it comes from the presidential candidate.

Trump endorsed exactly one primary candidate for Congress: Rep. Renee Ellmers (R-N.C.). She lost. The contest was a win for The Club for Growth, whose leaders detest Trump and who actively opposed Ellmers in her re-election bid.

Occasionally, it makes waves when a previous endorsement is withdrawn. Illinois Sen. Mark Kirk, a Republican, retracted his backing for Trump after the unsupported ethnic-based allegations against Judge Gonzalo Curiel.

Sometimes endorsements can represent poison wrapped as a gift, such as white supremacist David Duke’s embrace of the Trump campaign.

Republicans differed for years over whether conservative activist Pat Buchanan’s endorsement speech at their 1992 convention helped or hurt then-President George H.W. Bush.

One type of endorsement does generate buzz: surprise support from a supposed enemy. Sen. Bernie Sanders’ actions at the Democrats’ Philadelphia convention will be widely watched for where he casts his enthusiasm.

On the Republican side, Ohio Gov. John Kasich, whose state is hosting the GOP convention, hasn’t endorsed. He could still make a splash, depending whether he stumps for Trump or goes the other way.

But political veterans say a figure’s popularity, even if substantial, usually is not transferable to another person.