AUGUSTA — Lobbyists for the sports betting industry are training their sights on Maine lawmakers this week, hoping to convince them to override Gov. Janet Mills’ veto last week of a bill to legalize sports betting.

Betting proponents are highlighting the ongoing illegal market in Maine – and pointing to events in New Hampshire. The Granite State’s lottery commission approved sports betting and a contract with the online gaming company DraftKings in December and betting in that state, the second in New England to allow the practice, began in earnest in January.

New Hampshire saw 16,400 people register accounts with DraftKings, wagering more than $3.44 million in the first week of legal sports betting there, according to InDepthNH.org, an online publication of the New Hampshire Center for Public Interest Journalism.

“Early returns show that sports betting was absolutely the right bet for New Hampshire to make,” said New Hampshire’s Republican Gov. Chris Sununu. “With over $3.44 million already wagered here in the Granite State, and with revenues benefiting our state’s education system, this is already proving to be a big win. The demand is there and New Hampshire is happy to serve as the region’s go-to destination for sports betting.”

Mills vetoed a bill that would have legalized sports betting in Maine after she had held the bill for several months. In her veto message last Friday Mills said the bill was a “good effort” to bring illegal sports betting into the light of day, but was flawed by shortcomings, such as not providing harsh enough penalties for those who would violate the law.

In May 2018, the U.S. Supreme Court struck down a federal prohibition on sports betting, and since then a dozen states – including New Hampshire – have joined Nevada in allowing gambling on sporting events.

The only roll call vote Maine’s bill in 2019 took place in the Senate, which approved the measure by a vote of 19-15. At least 24 senators would have to disagree with Mills to override her veto, which requires a two-thirds vote in both the Maine Senate and House. Action on the veto override has not yet been scheduled but could take place later this week.

In her veto message, Mills said online entities, like DraftKings, have sophisticated methods of detecting underage or problem gamblers, but she questioned whether those strategies would be outweighed by sophisticated marketing online and with social media.

“These ads would unduly draw in people who should not be risking money impetuously because of youth or financial or family circumstances,” Mills wrote.

Estimates on how much sports betting would be worth in Maine varied widely, but a fiscal note attached to the bill suggests that if it were fully implemented, originally scheduled to occur in 2023, the state would collect as much as $5 million a year in fees and taxes. However, sports betting revenue forecasts fell dramatically short in several others states that legalized it in 2018 and 2019.

Supporters of the bill say millions of dollars in illegal sports betting, much of it online and with offshore entities, already is taking place in Maine without the state receiving tax revenue. Current estimates by those who study sports gambling in the U.S. suggest that as many as 263,000 Mainers are placing some $623 million in wagers each year with offshore betting agencies that are beyond the jurisdiction of state government and state taxes.

Maine’s sports betting bill gives just about every entity with an interest in gambling a slice of the revenue. The bill would allow casino operators, off-track betting parlors, harness racing tracks and Native American tribes in Maine to host sports betting operations.

Even if lawmakers override Mills’ veto, Mainers wouldn’t be legally betting on the Super Bowl next month, as the law would not go on the books until 90 days after the Legislature adjourns, which is not expected until mid- to late-April or early May. The state also would need time to write regulations.