Sen. Mitt Romney (R-UT) announced he will not seek a second term as senator. Most commentators remember him as the man who lost a winnable election in 2012 against Barack Obama and for being the sole Republican senator to vote to convict President Donald Trump during his two impeachment trials.

However, Romney has another legacy, one that will not redound to his credit. One night, during a primary debate, he single-handedly delayed a return to the moon program by at least four years, a full presidential term.

The controversy started on Jan. 25, 2012, when former House Speaker Newt Gingrich, then a candidate for president of the United States, promised that by the end of his second term the United States would have a base on the moon. He proposed that the base be created by a series of prizes and incentives, not as a typical NASA program such as Apollo or the then-recently defunct Constellation program proposed by President George W. Bush and summarily canceled by Obama.

Just a day later, during a debate between Republican presidential candidates, Gingrich’s moon base proposal ran into a buzz saw of criticism from the other candidates. However, Romney provided the coup de grace.

“I spent 25 years in business. If I had a business executive come to me and say they wanted to spend a few hundred billion dollars to put a colony on the moon, I'd say, ‘You're fired,’” Romney said. “The idea that corporate America wants to go off to the moon and build a colony there — it may be a big idea, but it's not a good idea.”

The use of a Donald Trump catchphrase in that cheap shot, considering Romney’s later ire against the then-reality show star and future president, was fraught with irony. Gingrich’s usual eloquence failed him at this point. In that moment, the moon base idea and the former speaker’s candidacy were as dead as JFK. Saturday Night Live even aired a mocking skit against Gingrich and the moon base.

The rest, as they say, is history. Romney, who had been endorsed by a group of former NASA and aerospace heavy hitters, went on to be defeated at the hands of Obama, a man who had once expressed disdain at the very idea of returning to the moon .

But in 2017, the newly elected Trump started the Artemis program to send astronauts back to the moon for the first time in decades and eventually to Mars. His appointed NASA administrator, Jim Bridenstine, used his considerable political skills to secure bipartisan support for the program. Part of Artemis, the human landing system, is being procured commercially from Elon Musk’s SpaceX. In 2023, it looks like the world, led by the United States, is headed back to the moon.

One can imagine an alternate history in which Gingrich had been faster on his feet, turning the mockery back against Romney for supporting, in effect, Obama’s anti-return to the moon position. Could Gingrich have gone on to win the Republican nomination? Could the former speaker have then gone on to beat Obama, a man as skilled in the politics of personal destruction as he was at using buzzwords such as “hope and change” to puff himself up? One can argue either way.

Still, the idea of a President Newt Gingrich starting a return to the moon program based on prizes and incentives in 2013 is a beguiling one. He would have had to sell the idea to Congress, which might have been skeptical of the plan’s novelty, not to mention the lack of opportunity for pork for campaign contributors.

But let’s say that something could have been cobbled together. Billionaires such as Elon Musk and Jeff Bezos might have relished a commercial race to the moon, spurred on by government prizes. A commercial moon base, with NASA just one of many customers, might have become a reality in 2020 in that alternate timeline.

Sadly, Mitt Romney, who is now bringing his political career to a close, ensured that the return to the moon still resides in the future and will not happen quite the way Gingrich imagined. It’s a dark stain on his legacy.

Mark Whittington, who writes frequently about space policy, has published a political study of space exploration titled Why is It So Hard to Go Back to the Moon? as well as The Moon, Mars and Beyond , and, most recently, Why is America Going Back to the Moon? He blogs at Curmudgeons Corner.   He is published in the Wall Street Journal, Forbes, the Hill, USA Today, the Los Angeles Times, and the Washington Post, among other venues.