Students react as President Obama takes the stage for a town hall with high school juniors, seniors and their parents at North High School in Des Moines, Sept. 14, 2015, to discuss college access and affordability and announce a change to the college financial aid system. (Andrew Harnik/AP)

Sixteen-year-olds nationwide would be allowed to preregister to vote under new legislation pushed by Democrats in Congress.

The move is backed by good-government groups, and its sponsors argue that it’s nonpartisan. But it fits into a national effort by Democrats to expand the electorate in 2016 in the face of more stringent voting rules and without President Obama’s galvanizing presence on the ballot.

“I was just amazed at the low voter turnout last November, especially among the younger people; that was just so discouraging,” said Rep. Don Beyer (D-Va.), who is introducing the bill Wednesday with Rep. Keith Ellison (D-Minn.).

The legislation would allow 16- and 17-year-olds to fill out voter-registration forms in advance, then be automatically added to voter rolls once they turn 18.

Young voters favor Democrats but also vote less reliably than their elders. Voter-identification requirements, which have been expanding across the country, are more likely to reduce young voters’ turnout.

Already in 20 states and in the District, younger teens can preregister to vote before their 18th birthdays. (North Carolina allowed preregistration until 2013, when it was repealed by a Republican legislature.)

A 2009 study found a modest effect on youth voter participation, depending on how actively states court eligible teens.

Voters in Maryland already can preregister to vote at age 16. But in Beyer’s home state of Virginia, which is far more critical battleground for both parties in next year’s presidential election, they cannot. Democratic officials in the state have been working on ways to blunt the effect of new voting restrictions in 2016, using this fall’s state legislative races as a testing ground for local and national efforts.

As lieutenant governor of Virginia in the 1990s, Beyer fought then-Gov. George Allen (R) over implementation of a federal mandate to allow voters to register at motor vehicle offices.

Allen lost in court, and the “motor voter” law went into effect. But Beyer noted Tuesday that teenagers who get their licenses at age 16 might not go back to the Department of Motor Vehicles for a decade.

Now, back in political office nearly two decades later, Beyer hopes to improve on that law.

Although preregistration itself would not cost much at all, the bill also would offer grants to states to educate teens on their new rights. Depending on how many states took advantage, that could cost as much as $25 million.

First, the bill would have to pass a gridlocked Congress, where voting laws have become a partisan issue. Former secretary of state and presidential candidate Hillary Rodham Clinton (D) has called for a sweeping expansion of voter access, including automatic registration for all 18-year-olds. Most prominent Republicans, though, support stricter regulations, which they argue are necessary to prevent fraud.

“This legislation has obstacles in this Congress, unfortunately,” said Dale Eisman, spokesman for the left-leaning government accountability group Common Cause. “But we’re always hopeful that folks will come around.”

Beyer argued that the bill would not necessarily help Democrats, arguing that wealthier teens might be more likely to get early driver’s licenses and to vote Republican.

“I’m not wildly optimistic, but I’m not pessimistic either,” Beyer said. “It’s a good idea, and good ideas ultimately happen.”