ATLANTIC CITY, N.J. — People began betting on which political party would win control of Congress in the November elections within minutes of a judge’s ruling Thursday allowing the bets — the only ones to be legally approved by a U.S. jurisdiction.

New York startup company Kalshi began taking what amounts to bets on the outcome of the November congressional elections after a judge declined to block it from doing so. The ruling enabled the company, at least temporarily, to offer prediction contracts — essentially yes-or-no bets — on which party will win control of the Senate and the House in November.

“The Kalshi community just made history, and I know we are only getting started,” said Tarek Mansour, a co-founder of the company.

It was not clear whether the company intends to offer bets beyond the ones posted Thursday for congressional races, including potentially taking bets on the presidential race. It also was not clear whether sports books or online casinos would seek to offer similar political bets in light of the ruling.

Prices on Kalshi’s so-called predictive contracts varied throughout the early afternoon. As of mid-afternoon, a bet on the Republicans to win control of the Senate was priced at 76 cents; a $100 bet would pay $129. A bet on the Democrats to win control of the House was priced at 63 cents, with a $100 bet paying out $154.

It was not clear how long such betting might last; the Commodity Futures Trading Commission, which last year prohibited the company from offering them, said it would appeal the ruling as quickly as possible.

Contrasting his client with foreign companies that take bets from American customers on U.S. elections without U.S. government approval, Roth said Kalshi is trying to do things the right way, under government regulation.

But Raagnee Beri, an attorney for the commission, said allowing such bets could invite malicious activities designed to influence the outcome of elections and undermine already fragile public confidence in the voting process.

“These contracts would give market participants a $100 million incentive to influence the market on the election,” she said. “There is a very severe public interest threat.”

The company already offers yes-no positions on political topics such as whether a government shutdown will happen this year, whether a new Supreme Court justice will be confirmed this year and whether President Joe Biden’s approval rating will be above or below a certain level by the end of the year.