An estimated 2 million people in Illinois could miss out on being automatically registered to vote if the state legislature does not override a recent veto by Republican Gov. Bruce Rauner.

Rauner this month vetoed SB 250, which would have enabled an Automatic Voter Registration (AVR) process for state residents. The measure garnered some Republican support and passed easily through both of the state’s legislative chambers on the last day of the legislature’s spring session.

Illinois legislators are scheduled to meet in November for a brief veto session, where the AVR measure will be considered. Talks with advocates for greater voter access stalled when the governor “insisted” that implementation of the AVR measure wait until January 2019, the Chicago Tribune reported. Rauner is up for reelection in November 2018.

AVR is an increasingly popular measure lawmakers nationwide have considered to eliminate barriers to voting, especially among historically disenfranchised and underserved groups. The measure transfers the responsibility of registration from voters to the government.

Legislators in Oregon, California, West Virginia, and Vermont have all passed AVR bills in the past 18 months. And lawmakers in dozens of other legislatures are considering following suit, according to the Brennan Center for Justice at the New York University School of Law.

Some AVR supporters believe Illinois legislators will exercise its power to override Rauner’s veto when the decision-making body convenes this fall.

Illinois residents complete voter registration applications at the Secretary of State’s Driver Services Department, which then transmits applications to local election authorities throughout the state.

The recently enacted Public Act 98-1171 allows residents to register when conducting business or interacting with the state’s Human Services, Healthcare and Family Services, Employment Security, and Aging departments. Rauner noted that while the measure was supposed to be implemented by July 1, the state had yet to complete the process.

Rep. Robyn Gabel (D-Evanston), who introduced the bill in the Illinois house, wrote on Facebook August 23 that Illinois must join other states that have passed AVR bills and expanded voter access. Gabel said she would push to override Rauner’s veto or pass new AVR legislation.

If legislators override the governor’s veto, the AVR measure would require state officials to automatically process voter registration for each person for whom it has information starting July 1, 2017. Other agencies would have to follow suit by January 1, 2018. The person would then be notified about the automatic registration and could opt out if they desired.

SB 250 would also require the state elections board to cross reference certain information about eligible voters at least six times annually.

Rauner, in a veto message released August 12, said he strongly supported efforts to remove barriers to voting and to simplify and modernize voter registration, but couldn’t support SB 250 for an array of reasons.

The governor suggested the bill could threaten the integrity of Illinois’ election system and cited a few instances of voter fraud. A recently released nationwide study showed that instances of voter fraud are “infinitesimal compared with the 146 million voters registered” between 2000 and 2012.

The Brennan Center for Justice said its ongoing examination of national elections shows that voter fraud is very rare and that voter impersonation is nearly non-existent. The Center, which released a study about voter fraud in 2007, contends that unintentional mistakes by voters or election administrators cause most problems associated with alleged fraud.

“Voter fraud remains rare because it is irrational behavior,” Lorraine Minnite, a political science professor at Rutgers University-Camden, said in an interview with NBC News. “You’re not likely to change the outcome of an election with your illegal fraudulent vote, and the chances of being caught are there and we have rules to prevent against it.”

Cook County Clerk David Orr said at a press conference held this month that his county, the largest in Illinois and one of the largest in the United States, did not have a problem with undocumented citizens committing alleged voter fraud, according to Chicago magazine.

Rauner said in his statement that he returned the bill to the Illinois General Assembly because sponsors and proponents needed to make important corrections to comply with the federal National Voter Registration Act and to give the State Board of Elections “adequate time and resources” to implement the bill’s provisions.

“The proponents of the bill intend to remove barriers to voting, which I applaud,” Rauner said in his veto statement. “But in the haste of amending and passing the bill on the last day of the spring legislative session, they concede that the bill does not plainly and clearly describe the process they envision.”

Rauner lamented that the bill relies on the State Board of Elections to screen out people who are ineligible to vote because the state board may not have access to that information. He criticized the fact that agencies would have to check their own records to confirm that a person is eligible to vote and tell the elections board which identification documents they checked to verify a resident’s eligibility.

Rauner noted that bill relies on agency records to be “accurate, consistent, and reliable.”

Rauner’s veto comes a few months after he signed SB 1529, which he said “enhances criminal penalties for fraudulent voting” and allows the use of digital voter signatures and the expansion of online voter registration, among other election-related changes.

Common Cause Illinois, a government watchdog organization, has accused Rauner of trying to delay the AVR bill beyond the fall 2018 election, where he is expected to appear of the ballot for re-election, according to the Chicago Tribune.

Just Democracy Illinois, a coalition of local nonprofit organizations, including Chicago Votes, Latino Policy Forum and the American Civil Liberties Union of Illinois, leveled criticism for Rauner’s veto of the AVR policy.

Oregon was the first state to pass and enact an AVR law. The state passed the “motor voter bill” in March 2015 and enacted the law in January. As a result of the new measure, nearly 52,000 residents in four months were registered to vote, according to a Associated Press report released in May.

Lawmakers in California last September passed a bill modeled after Oregon in effort to address the 6.6 million eligible but unregistered voters living in the state, according to the Brennan Center for Justice.

Illinois is not the only state where the governor vetoed a AVR bill after overwhelming support from a state legislature.

New Jersey Gov. Chris Christie (R) has twice vetoed an ARV measure because of the purported threat of voter fraud. Christie referred to the bill, A1944, as the “The Voter Fraud Enhancement and Permission Act” and said it came with a $400,000 annual price tag and a $1 million fee to implement, according to NJ.com.