In his new book, then-New Hampshire Gov. John H. Sununu (R) credits his distribution of low-digit (i.e. desirable) license plates with helping his ally George H.W. Bush win the state in a competitive 1988 Republican  primary.

That's right, license plates. And New Hampshire isn't alone. In several states we've researched, low-number plates -- the less numerals, the better -- are a way to show off your political connections. That's because in states like New Hampshire, you can't just walk into a DMV and request one; you have to know someone to give you the plate. It's supply-and-demand: The more difficult something is to acquire, the more valued it is. (Think of low-digit license plates as the political equivalent of a Hermes Birkin bag.)

And Sununu handed these two- and three-digit plates out like promises of Cabinet positions in exchange for Granite State operatives' support for Bush over his main primary challenger, Sen. Bob Dole of Kansas.

"As we rode around the state encouraging the more influential political figures to join us on the Bush team, we quickly discovered that whenever one of the more desirable opinion leaders was having trouble deciding whether to support Bush or Dole, the promise of a low-digit license plate was a very effective tie-breaker."

Apparently low-digit license plates are still a thing. In 2010, New Hampshire Magazine talked with low-digit license plate holders who compared it to the highest of honors (h/t our book editor, Carlos Lozada):

"According to what I’m told, the lowest number plates show you’re the crème de la crème and an ‘in’ in the state of New Hampshire,” says State Sen. Andre Martel of Manchester. “I guess in some people’s eyes it’s the closest thing to being The Pope."

In Connecticut, low-digit license plates were also distributed in a nebulous way -- thus increasing their prestige. But then came a 2011 scandal revealed by Hartford Courant columnist Kevin Rennie, who quoted 1990s DMV commissioner Lou Goldberg as refusing an attractive woman who offered him sex in exchange for a license plate.

The woman "offered to spend the night with me if I gave her a low-digit plate. … She said she wanted to give it to her boyfriend," Goldberg allegedly said.

No surprise: Connecticut's DMV suspended handing out the license plates soon after, and last year debated holding an auction program (as in Texas) for specialized plates. The plates would still be a treat for the rich -- the most expensive plate ever sold in Texas was a $115,000 one supporting Texas A&M Aggies (figures) -- but not necessarily for the rich and politically connected.

But how is it legal for government officials to hand out government property to promote political causes? The law experts we talked to weren't 100 percent sure, but they said it sounds like that's AOK with campaign finance law.

"It's unseemly," said Darrell West, Brookings Institution's governance studies expert. "But it's not likely to be illegal."

That's because it is legal for states to give money to political parties, said Columbia Law Professor Richard Briffault, an expert in campaign finance and government ethics issues. In some states, such as Idaho and Iowa, taxpayers can check off $1 or $2 on their tax returns to go to a local political party. In others, the money goes to a general fund where the state distributes the cash in a pre-designated formula among political parties. Indiana's two major political parties got up to $750,000 a year each from the DMV for the sale of vanity license plates, Governing Magazine's Alan Greenblatt reported in 2004.

The law even survived a Supreme Court challenge. In the landmark 1976 campaign finance case Buckley v. Valeo, justices upheld the constitutionality of giving government money to candidates.

But where the legal-license-plate-hand-out-slope gets extra slippery is when government officials use government property -- like hard-to-get license plates -- to promote just one candidate. Sununu appears to have repeatedly admitted to doing just that. As governor of New Hampshire, he handed out government-issued license plates to try to get Bush elected.

"I can't tell you it's illegal,"  Briffault said, "but it certainly seems improper."

Neither we nor the law experts we talked to could find any instances of politicians being prosecuted for doing such a thing. And in fact, when Connecticut was shelving its low-digit license plates, the state's DMV head seemed to have no remorse about the program.

"I absolutely [would] not apologize for giving a fellow Democrat a two-digit or three-digit plate," DMV Commissioner Melody Currey told the Hartford Courant's Jon Lender.

Perhaps Sununu himself -- who went on to have a long and storied career as Bush's chief of staff -- explains the murky situation best. Politicians operate on leverage, and rare license plates that people inexplicably go ga-ga over is just one more way to get what you want.

“That’s what politics is all about," he wrote. "And that’s why governors have currencies, in the plural, that make for political strength in campaigns.”