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(Reuters) -Abortion rights advocates are working to place the issue on ballots in nearly a dozen U.S. states in November's election, including several expected to play central roles in the presidential race and the battle for control of Congress.

Democratic candidates - from President Joe Biden to members of Congress to state legislators - also are trying to build support for the measures, which they believe will galvanize left-leaning and independent voters.

The list of states includes Arizona, which is likely to be a critical swing state in the presidential contest between Biden and Republican former President Donald Trump and will feature a competitive Senate race.

Abortion rights will also appear on the ballot in Nevada, where another high-profile Senate election will take place, and Florida, a one-time battleground state that Democrats say could be back in play after the state Supreme Court upheld a six-week ban.

Anger over the U.S. Supreme Court's decision to eliminate a nationwide right to abortion in 2022 has been widely credited with boosting Democrats' performance in that year's midterm elections, as well as in statewide races in Kentucky and Virginia last year.

Since the court ruling, every statewide ballot measure—seven in all—has gone in favor of protecting or expanding abortion access, including in conservative strongholds like Ohio and Kansas.

Here are the states where abortion could be on the ballot on Nov. 5:

ARIZONA

Arizona for Abortion Access, a coalition of reproductive rights groups, said it had collected more than 500,000 signatures as of the beginning of April, far more than the approximately 384,000 needed by July to put a measure on November's ballot that would guarantee abortion rights.

If approved, the referendum would amend the state constitution to protect abortion rights up to fetal viability, generally around 23 or 24 weeks.

The issue of abortion was thrust to the forefront of the state's politics in April, when the state Supreme Court ruled that an 1864 near-total ban—enacted nearly 50 years before Arizona became a state—could take effect. The decision energized Democratic voters and drew more attention to the referendum effort.

The state legislature repealed the law weeks later, after a handful of Republican lawmakers voted with the Democratic minority. Abortions are subject to a 15-week ban passed in 2022 after the U.S. Supreme Court decision.

FLORIDA

The state Supreme Court on Apr.1 approved a ballot measure, backed by reproductive rights groups, asking voters whether to amend the state constitution to protect abortion access.

In a separate ruling, the court upheld the state's existing 15-week abortion ban, a decision that also cleared the way for a more stringent six-week limit to take effect on May 1.

State Attorney General Ashley Moody, a Republican, had asked the court to block the referendum as misleading and vague, but four of the seven justices—all conservatives—disagreed.

Unlike most states, constitutional amendments in Florida must pass with at least 60 percent of the vote, a higher threshold of support than any statewide abortion measure has yet received.

Once a perennial battleground state, Florida has leaned Republican in recent elections, voting twice for Trump and electing Governor Ron DeSantis in a landslide in 2022.

Biden's campaign says it believes he can win Florida following the state Supreme Court's decisions.

NEVADA

The coalition behind a constitutional amendment to protect abortion rights submitted more than 200,000 signatures to the secretary of state's office on May 20, almost double the minimum number required to qualify the measure for November's ballot.

State law already offers similar protections, but adding them to the state constitution would make it harder to roll those rights back. Voters would need to approve the measure twice—this year and again in 2026—to amend the constitution.

OTHER STATES

In Missouri and South Dakota, both deeply conservative states where virtually all abortions have been banned, organizers have collected enough signatures to qualify ballot initiatives that would add abortion rights to state constitutions. South Dakota's secretary of state said on May.!6 that her office had validated the petitions, clearing the way for the measure to go before voters.

Similar campaigns are under way in Arkansas, where abortion is outlawed, and in Nebraska, where abortions are largely illegal after 12 weeks of pregnancy.

A constitutional amendment will also be on the ballot in Colorado, after state officials announced the measure had qualified. In Montana, advocates are still collecting signatures for an abortion rights referendum. Both states already allow abortions, but supporters say that adding protections to the state constitutions would ensure that lawmakers or courts could not limit abortion rights in the future.

While not a presidential battleground, Montana is expected to see a highly competitive U.S. Senate race this year.

There are two states in which lawmakers have approved abortion-related amendments for November's ballot: New York and Maryland. In both states, abortion is already legal under state law, and the Democratic-controlled legislatures have approved referendums that would amend their state constitutions to add additional protections.

However, a New York judge struck the measure from the ballot in that state in May, ruling that lawmakers had not followed proper procedure when approving it. The state's Democratic attorney general, Letitia James, said she would appeal.

(Reporting by Joseph Ax; Editing by Colleen Jenkins and Jonathan Oatis)