Senate Democrats are calling on the administration to crack down on political betting markets, which have flourished in recent years despite theoretically being outlawed federally.

In recent years, sites like PredictIt and Smarkets have grabbed headlines for keeping odds on the outcomes of political events like elections and allowing bettors to wager on these outcomes and even trade shares predicting certain outcomes.

On Wednesday, for instance, shares predicting Vice President Harris will win the election are trading for 56 cents each on PredictIt, while shares predicting a victory by President Trump are trading for 47 cents. This means bettors favor Ms. Harris slightly at the moment.

Now, a group of congressional Democrats, including Senator Warren and Congressman Jamie Raskin, are calling on the Commodity Futures Trading Commission to crack down on political betting markets.

“We strongly support the proposed rulemaking to prevent further corruption of our electoral system by moneyed interests,” a letter from eight Democrats reads. “Election gambling fundamentally cheapens the sanctity of  our democratic process. Political bets change the motivations behind each vote.”

The letter has elicited some backlash from fans of political betting, which is often talked about by bettors, followers of politics, and election handicappers. Yet it’s notable that political betting is already theoretically outlawed in America.

Regulations on futures trading passed in 1936 and other New Deal-era financial regulations largely stamped out political betting markets, which were common in the early 20th century. Some states have also banned the practice.

However, regulations left a loophole for markets that ostensibly are dedicated to research purposes, which is how sites like PredictIt operate today. PredictIt is a New Zealand-based company that is owned and operated by Victoria University of Wellington and a company called Aristotle.

The members of Congress, in their letter, express support for rulemaking following a ruling made in late 2022 that the site was no longer operated “for academic purposes only.”

As it stands, there’s not a clear timeline for potential new regulation of election betting. Yet the issue is likely to gain prominence as the election draws near. Most bets so far in 2024 have been on PredictIt, with bettors placing some $500 million on the presidential election alone.

Tied to potential regulation of PredictIt is the company’s shaky reputation among some bettors. The Bettor Business Bureau gives the company an “F” rating, mostly because of issues with the site paying out bettors.