The federal Election Assistance Commission was formed after the disputed 2000 election between George W. Bush and Al Gore and given an innocuous name and a seemingly inoffensive mission: to help state election officials make it easier to vote.

In this poisonous, ideologically riven election season, it turns out, that is not easy at all.

The election commission is in federal court this month, effectively accused of trying to suppress voter turnout in November’s elections. The Justice Department, its nominal legal counsel, has declined to defend it. Its case instead is being pleaded by one of the nation’s leading advocates of voting restrictions. The agency’s chairman has disavowed its actions.

The fracas exemplifies a moment when the mere civic duty of voting has become enmeshed in the volatile partisan politics that dominate the 2016 campaign. Seventeen states will have new voting restrictions in place for the presidential election in November. Many are the object of bitter disputes between those who say they are rooting out voter fraud and those who say the real goal is to keep Democratic-leaning voters from casting their ballots.

The lawsuit’s origin is straightforward. The agency’s executive director, Brian D. Newby, had been in his job less than three months in January when he unilaterally reversed a policy that the body’s commissioners, two Democrats and two Republicans, had endorsed since the agency’s creation in 2002: that people registering to vote need offer no proof, beyond swearing an oath, that they are American citizens.

That decision gave Kansas, Georgia and Alabama officials a blessing to alter the federal voter registration applications handed out in motor vehicle offices and many other state agencies and to replace the oath with something stiffer: a demand for proof of citizenship, such as a birth certificate.

There was but one problem, critics say: Newby had no authority to make policy, a power reserved to the agency’s four commissioners.

Newby calls the approvals an administrative matter, not a policy issue. And he has said that he did not change the registration form, but merely its instructions, although federal administrative code calls the instructions part of the form.

“It wasn’t a ruling so much as a response to a request,” he said. “I wasn’t looking at it through the lens of proof of citizenship. I was looking at it as state law that necessitated changes in the instructions.”

Critics see something very different.

“It’s trench warfare in the battle of voter suppression,” said Lloyd Leonard, the advocacy director of the League of Women Voters, the leader of the lawsuit against the commission.

Whatever the case, a head-scratching legal battle has ensued. The Justice Department refused to defend Newby’s decision, arguing that his actions were clearly illegal. Newby’s defense was assumed by the Kansas secretary of state, Kris Kobach — a former Republican Party chairman in one of the nation’s most conservative states, and perhaps the leading advocate of tightening requirements for registering new voters.

The fracas has raised eyebrows for another reason: Newby came to the commission from suburban Kansas City, where he was an election commissioner appointed by and answering to Kobach. In an interview, Kobach said any suggestion that he had orchestrated Newby’s decision was ridiculous.

A decision on whether to issue a preliminary injunction over Newby’s action may come soon, but the battle is unlikely to end. Kobach twice has taken a crusade for requiring proof of citizenship to the Supreme Court, and twice lost. Many expect this case to end there as well.

Critics say Newby’s action is the exact opposite of what the commission was formed to do.

“If the Newby decision stands, then every state in the nation will be able to require documentary proof of citizenship” said Leonard of the League of Women Voters. He said that would force tens of thousands of eligible voters off the rolls in those states, many of them poor and elderly, who do not have documents required to register or the time, resources or energy to obtain them.

The disputed forms involve only federal elections; states are free to require ID from people registered to vote in local races. In Kansas, where proof has been required on state registration applications since 2013, state records indicate that at least 30,000 applicants have been denied registration for lack of documents. Advocacy groups say the true number could be 45,000 or more, but because the state purges its roll of denied voters every 90 days, the actual total is unknown.

New constraints on voting in 17 states, in effect this year for the first time in any presidential election year, include requirements to present photo identification or proof of citizenship, shortening early-voter periods and reducing the number of polling places for early voting.

The authors of these measures, almost always Republican legislators, say they seek to curtail rampant fraud in voting booths. Political scholars say the kind of fraud that many of the measures attack — voting by undocumented immigrants or out-of-state residents — is practically nonexistent. Kobach maintains that false registration is far more common.

“We presented to the Election Assistance Commission a list of 18 noncitizens in a two-year period in just one county who had either successfully registered or attempted to register,” he said.

Democratic politicians and voting-rights advocates argue that the restrictions are intended to suppress the turnout of predominantly Democratic supporters — the poor, immigrants, students, African-Americans and Hispanics among them — who are less likely to have the required documents and are least able to get them easily.

The election assistance commission’s mandate has been to advise states on voting issues, including updating outmoded voting machines. A bipartisan body — it has two Republican commissioners and two Democrats — it was meant to make voting easier and less controversial. But Republicans in Congress later decided the commission was not needed, and it languished for more than three years without confirmed commissioners.

When it was revived, the commissioners hired Newby after a national search. Thomas Hicks, a Democratic commissioner who is its chairman, said Kobach had not influenced Newby’s hiring. “This was an extensive process that we all took seriously,” he said. “It wasn’t done lightly, and it wasn’t done overnight.”

The standoff at the commission centers on the 1993 National Voter Registration Act, the so-called motor-voter law, which mandated that a single voter-registration form be distributed in motor vehicle bureaus and other state offices nationwide. The law requires that people registering to vote swear under penalty of perjury that they are American citizens.

The election commission has twice rejected requests by Kobach to change the form to require documentary proof. In 2012, he supported the Arizona secretary of state, Ken Bennett, in a lawsuit seeking discretion to reject registrations using the form if no proof of citizenship was presented. But in a 7-2 decision written by Justice Antonin Scalia, the Supreme Court ruled that the 1993 law forbids states to require additional information beyond what is on the form. Kobach later sued the election commission on a related issue, but a federal appeals court ruled against him and the Supreme Court refused to hear the case.

But when Newby became executive director in November, a third request for the change by Kobach, as well as similar requests from Georgia and Alabama, were awaiting action. Without hearings or consultations with commissioners, Newby sent letters on Jan. 29 telling them to go ahead.

Hicks quickly demanded that the approvals be withdrawn, noting that the commission had stated in 2015 that its executive director may enforce policies, not make them.

For his part, Newby said his relationship with Kobach had played no part in his decision, and he noted that he had been appointed and reappointed in Kansas by both Republican and Democratic officials. “I’m the same person” as the one who ran elections in Kansas City, he said. “I was grounded by the same philosophy I was grounded in in Johnson County,” he said.

The groups that filed suit scoff at that.

“This is an attempted end run” around the bipartisan consensus required for the commission to approve policy changes, said Wendy R. Weiser, a lawyer for the plaintiffs and the director of the Democracy Program at the New York University School of Law’s Brennan Center for Justice.

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