Sports gambling companies, California tribes and card rooms have spent more than $410 million for and against Proposition 26 and 27. The former would allow in-person sports betting at tribal casinos and horse racetracks. The latter would allow online sports betting on platforms run by tribes and gaming companies.

Early this month, neither looked likely to pass. Only 31 percent of voters supported Proposition 26, and even fewer — 27 percent — supported Proposition 27, in a poll from the UC Berkeley Institute of Governmental Studies.

But in a more recent poll conducted by SurveyUSA for The San Diego Union-Tribune and KGTV 10News, support for Proposition 26 had grown to 43 percent of likely voters, compared with 32 percent opposed. Proposition 27 still looked unlikely to pass with 37 percent of voters in support and 43 percent opposed.

Both measures performed better among those who regularly bet on sports or visit tribal casinos, according to the poll. They were also more likely to be supported by voters who were more familiar with the propositions and understood the difference between them.

Leaders of four of California’s most successful Native American tribes with gaming interests are the original proponents of Proposition 26, the in-person sports betting measure. It would impose a 10% tax on sports betting to fund gambling addiction treatment and enforcement programs.

A coalition of more than 30 tribes support Proposition 26, with major funding from the Agua Caliente Band of Cahuilla Indians in Palm Springs, the Barona Band of Mission Indians in Lakeside and the Yocha Dehe Wintun Nation in rural Yolo County.

Proposition 27 is funded by gambling corporations, including sports gaming companies DraftKings and FanDuel. The companies, which control a large swath of the online sports betting market in the U.S., would be required to partner with a California tribe and pony up $100 million to get licensed in the state. Tribes could also offer sports betting platforms on their own for a $10-million entry fee.

Tribes and gambling companies with sports betting licenses would pay 10% of their take from sports bets each month to the state, after subtracting some expenses and losses. The initiative would direct the revenue to fund programs for homelessness and gambling addiction, with a smaller cut for tribes that are not involved in online sports betting, according to the Legislative Analyst’s Office.

If both propositions receive more than 50 percent approval, the one with the most votes wins.

Despite the increase in support for the propositions, 41 percent of voters think expanding access to gambling would be bad for the state compared to 37 percent who said it would be good, according to the SurveyUSA poll.

The poll also found that Gov. Gavin Newsom and Senator Alex Padilla are well-ahead in their re-election bids, with both Democrats ahead of their Republican opponents by 22-point margins.