Congress is moving to pass the biggest new sales restrictions on tobacco products in more than a decade, with support from two unlikely backers: the Marlboro cigarette maker, Altria, and the vaping giant Juul.

The legislation would raise the minimum age to purchase all tobacco products, including electronic cigarettes, from 18 to 21 nationwide, a step long sought by health advocates. But in the past year Juul and Altria have emerged as the biggest supporters of the measure, blanketing Capitol Hill with lobbyists and advertisements touting their support for the “Tobacco 21” law.

Tobacco critics contend the companies’ support is calculated to head off even harder-hitting government action: a ban on all flavored products, including fruit and dessert e-cigarettes.

“Altria and Juul clearly support this in order to argue that no other action is necessary,” said Matthew Myers of the Campaign for Tobacco-Free Kids. “If you don’t eliminate the flavors that the industry has used to fuel the epidemic, you won’t solve the youth e-cigarette crisis.”

The bipartisan legislation, supported by the Senate majority leader, Mitch McConnell of Kentucky, has been attached to a package of must-pass spending bills that will keep the government running into next year.

Juul and Altria, the vaping company’s biggest investor, threw their support behind the effort this year amid a backlash against e-cigarettes at the local, state and national levels.

Current federal law prohibits sales of e-cigarettes and all other tobacco products to those under 18. But more than one in four high school students report vaping regularly, according to the latest government figures. And health officials have called the vaping trend an “epidemic”.

Until September, Juul argued that its sweet flavors, including mango, mint and fruit, could help adult smokers switch from traditional cigarettes to vaping. But the company dropped that message as Donald Trump announced plans to remove virtually all vaping flavors from the market, due to their appeal to children. The Silicon Valley company has halted sales of all but two of its flavors, menthol and tobacco, and pledged not to oppose Trump’s plan.

But momentum for the nationwide ban has faded amid pushback from vaping advocates and conservative groups. And Trump has voiced support for alternative approaches to keep e-cigarettes away from kids, including raising the purchase age to 21. The age hike is expected to limit the supply of all vaping and tobacco products in high schools by putting them out of reach to 12th graders.

Myers’ group and other health advocates say Congress should both raise the age limit and ban all “kid-friendly” flavors.

Even with most of Juul’s flavors off the market, smaller companies continue to market an array of flavored products, including “grape slushie”, “strawberry cotton candy” and “sea salt blueberry”. And the industry’s main trade association is suing to keep e-cigarettes, including flavors, widely available.

Altria, the nation’s largest tobacco company, said it supports a “clean” Tobacco 21 bill focused exclusively on raising the age limit because it is the “quickest and most effective” way to address the recent surge in teen vaping. For decades previously, Altria and other tobacco companies aggressively defended the 18-year-old minimum purchase age.

Juul has similarly supported legislation that raises the purchase age without touching flavors. And while the companies say they lobby separately, both quickly backed the Tobacco 21 bill introduced in May by McConnell and the Virginia Democratic senator Tim Kaine.

Juul vaping supplies on sale in New York. Youth vaping has been called an ‘epidemic’. Photograph: Richard Levine/Alamy Stock Photo

The companies’ support sapped attention away from other proposals that would have gone much further. For example, a bill from the New Jersey Democratic congressman Frank Pallone would have banned flavors from all vaping and tobacco products, including menthol cigarettes, and prohibited online sales. The bill was endorsed by a dozen health groups, including the American Academy of Pediatrics, the American Cancer Society and the American Lung Association.

“Flavors attract kids, and kids are the tobacco industry, including the e-cigarette industry’s, future,” said Erika Sward, a vice-president with the American Lung Association.

The logic for hiking the purchase age for cigarettes is clear: most underage teens who use tobacco get it from older friends. An estimated 90% of smokers start before age 18.

Delaying access to cigarettes is expected to produce major downstream health benefits, with one government-funded report estimating nearly 250,000 fewer deaths due to tobacco over several decades.

Still, anti-tobacco experts say age restrictions are only effective when they are vigorously enforced, and tobacco sales can fall through the cracks amid a patchwork of local, state and federal law enforcement. They point to underage drinking as an example of the limited impact of age-based restrictions.

State laws banning tobacco sales to those under 18 evolved over several decades and were reinforced by a federal law in 2009. The same law banned all flavors from traditional cigarettes except menthol, which received a special exception at the behest of tobacco lobbyists.

More than a third of US states including California, Illinois, New York and Texas and the District of Columbia have already raised their minimum purchase age to 21. Anti-smoking groups have tracked the trend with measured support, noting the role of Juul and Altria lobbyists behind many of the efforts.

In Washington DC, Juul’s lobbying budget ballooned to more than $3.1m in the first nine months of 2019, nearly twice the company’s spending for all of 2018. Altria has spent $7.4m in 2019, roughly even with its lobbying budget for 2018. The company’s political action committee and employees have given $37,000 to McConnell’s 2020 re-election campaign, according to federal records compiled by the not-for-profit Center for Responsive Politics.