Maryland voters are sharply divided over a ballot proposal that would allow a Las Vegas-style casino in Prince George’s County, according to a Washington Post poll that shows widespread doubt that the measure would boost education funding as advertised.

Among likely voters, 46 percent say they favor Question 7, while 48 percent say they oppose the measure, which would also allow table games, such as blackjack and roulette, at the state’s five previously authorized slots sites.

In Prince George’s, likely voters divide 52 percent in favor and 44 percent opposed, an apparent lead, but not a significant advantage given the number of interviews in the county. Under a law adopted this year, the new casino is not supposed to move forward without the blessing of the host jurisdiction.

Read the full poll results.

Gambling companies on both sides of the issue have poured more than $50 million — an amount unprecedented in Maryland politics — into campaigns to win votes. And the poll suggests the advertising blitz has moved some voters to oppose the expansion.

Maryland referendum primer

Nearly two-thirds of likely voters have heard or seen “a lot” of ads on the issue, and more than half, 55 percent, say they are not confident the expansion plan will produce more money for schools — a doubt central to the opponents’ campaign.

At the same time, a slim majority of registered voters, 52 percent, say Maryland’s existing slots program has been a “good thing” for the state. About half as many, 27 percent, see the program as a “bad thing,” while the remaining 22 percent have no opinion or see the effect as mixed.

The 2008 referendum that launched Maryland’s slots program passed in a landslide, 59 percent to 41 percent.

Bill Miller, an aircraft mechanic from St. Mary’s County, is among those who are inclined to vote “no” this time, even though he said he has no objections to gambling in general.

“I’m not sure where all the money is going to go, how much the school system is going to get,” said Miller, 47.

As for all the ads? “I don’t know what to believe anymore,” Miller said. “They bombard you so much.”

MGM Resorts, which is angling to build a casino at National Harbor, the mini-city on the Potomac River, has emerged as the largest funder of the campaign to pass Question 7, contributing more than $21 million so far. The pro-expansion ads have touted the promise of new jobs and more money for education.

Under Maryland law, gambling proceeds are divided among the casino operator, the state and the host jurisdiction.

The sole funder of the opposition campaign is Penn National Gaming, which owns a casino in Charles Town, W.Va., that analysts say would take a hit if another large-scale venue opens in neighboring Maryland. Penn has given more than $25 million.

Reginald Calloway, a retired chef from Germantown, is among those that the proponents of Question 7 have in their corner.

Calloway said he likes to play slots and heads to Charles Town to do so a couple of times a year. If a casino opens in Prince George’s, Calloway, 63, said he would go there instead.

Moreover, he said, the addition of a new casino and table games will create much-needed jobs.

“With the unemployment rate the way it is in the state of Maryland, people need work,” Calloway said.

Casino gamblers express wide support for the referendum. Six in 10 likely voters who have visited a Maryland casino in the past year support the expansion, as do 74 percent of voters who say they’d visit a casino at National Harbor at least rarely, if it were built.

Should the measure pass, 11 percent of registered voters say they would visit the proposed casino at National Harbor frequently or occasionally. That rises to 24 percent in Prince George’s, home to the proposed facility.

But concerns about less-than advertised funding for education and gambling’s impact on crime and other problems are fueling opposition to Question 7.

Fewer than half of all voters, 43 percent, are confident that additional casinos will produce more money for schools, with just one in 10 “very confident.” One in four voters are “very concerned” that the expansion of casino gambling will lead to more crime and problems like gambling addiction.

And among likely voters who doubt benefits to schools or express deep concern about crime and other problems, more than three-quarters oppose the gambling expansion.

The Post poll detects only small partisan differences on the issue — 49 percent of Democrats support the gambling expansion, along with 42 percent of Republicans and 45 percent of independents.

A slim majority, 52 percent, of black voters support the measure, compared with 43 percent of white voters.

And younger voters are more likely to support Question 7. Support is highest among those ages 18 to 39, at 62 percent. That drops to 41 percent for those ages 40 to 64; and 38 percent for those 65 and older.

The telephone poll was conducted Oct. 11 to 15 among a random sample of 1,106 Maryland adults. Interviews were conducted on landline and cellular telephones and in English and Spanish.

The samples of 934 registered voters and 843 likely voters each have a margin of sampling error of plus or minus four percentage points.

Related: County executives tout Md. gambling plan in new TV ad

Jon Cohen and Peyton M. Craighill contributed to this report.