Democrats may have lost control of the governor’s mansion during the November midterms, but they won a separate battle that could be beneficial down the road: voter-rights expansions.

Not only did Illinois citizens approve a constitutional change meant to negate voter-identification laws, but the Democrat-run legislature passed a bill allowing potential voters to register at the last possible second — when they cast their ballots on Election Day.

Outgoing Gov. Patrick J. Quinn is expected to sign the measure, which makes permanent some changes that were used for the first time in November, before leaving office in January.

And although he was ousted last month by Republican Bruce Rauner, an expanded pool of voters could be a boon to his fellow Democrats in future elections.

“I think it’s pretty safe to say, if anything, it’s going to help Democrats,” said Christopher Mooney, director of the Institute of Government and Public Affairs at the University of Illinois.

“Their demographic is younger and poorer, and Republicans tend to be the more settled, well-off people. It’s the same thing with voter-identification laws — if you’ve been working at the bank 30 years or own a car dealership or something, you’re going to have a (voter) ID.”

Mooney said there are exceptions to those broad demographic trends.

“Of course you’re going to find some guy who’s homeless and is going to vote no matter what. But what we’re talking about are the tendencies at work,” he said.

Brian Gaines, a political science professor and expert on state politics at the University of Illinois, said it’s difficult to pin down exactly which voters will be mobilized by easier registration.

He said he agrees same-day registration would likely give a “slight edge” to Democrats, but voters who turn out in future elections because the process becomes easier are probably not bound to one particular party.

“Such voters are more likely to (favor) incumbents, of either party, and to go with the flow in big-tide years,” such as 2008 for Democrats or 2010 for the Republicans, Gaines said in an e-mail.

Aside from that, demographic party preferences are constantly changing. Recent studies have shown, for instance, that young people who for years have typically been counted as Democratic voters in need of a push to the polls may be less inclined to vote that way.

And those who hardly ever vote will probably continue to avoid doing so, he added.

“A lot of these people just hate politics and aren’t going to flock to the polls because registration got a bit easier,” Gaines said.

The constitutional change — which says no one should be denied the right to vote based on “race, color, ethnicity, status as a member of a language minority, national origin, religion, sex, sexual orientation, or income” — passed with mostly bipartisan support.

But the registration bill, Senate Bill 172, which also calls for an extension of early voting hours and grace-period registration on college campuses, was sharply contested along party lines.

And while pushing a few more college students or minorities to the polls in subsequent elections won’t necessarily change things drastically, even marginal changes can be consequential.

Take this year’s treasurer’s race: Democratic Sen. Mike Frerichs, of Urbana, defeated former state House GOP leader Thomas H. Cross III, of Oswego, by a little more than 9,000 votes, according to unofficial tallies.

That’s about the exact number of people who registered or changed their registration information on Election Day through the trial-run of same-day registration that was provided in Chicago and some of the collar counties.

The numbers are laid out in a report released this month by The Chicago Lawyers’ Committee for Civil Rights Under Law — a nonprofit consortium of law firms — and other groups, which surveyed voters and supports the idea of expanding same-day registration.

“First, Election Day voter registration is very much needed to provide equal access to the polls.

“And second, it is critical that the Illinois General Assembly allocate more resources toward (same-day registration) than it was given during the pilot program,” said the group’s staff attorney, Ruth M. Greenwood, in a statement about the results of its survey.

“The pilot program was highly utilized, and election jurisdictions were not always able to keep up with demand on Nov. 4.”

Sen. Donald F. Harmon, a Democrat from Oak Park, sponsored the legislation.

He said in a statement that he thinks “we should do everything we can to make voting easier. The more people who vote and participate in government, the better.”