Independent Sen. Kyrsten Sinema faces an uphill battle and a dwindling timeline if she wants to run for re-election.

Why it matters: The first-term senator, who left the Democratic Party in 2022, has remained tight-lipped about her political future.

• If she decides to run, she'll set up a rare three-way competitive contest in a race that could determine control of the U.S. Senate.

The latest: Signature-filing deadlines for candidates were moved up a week as part of the Legislature's recent fix to avoid election deadline issues, further tightening Sinema's window to qualify for the ballot.

Zoom in: She must file about 42,000 valid signatures from Arizona voters by April 1. That's six times the signatures required for candidates running with a party.

• Before she can start collecting signatures, she must file a "statement of interest" with the Arizona Secretary of State's Office, which she has not done.

The intrigue: Local consultant Meghan Cox, who has organized major signature campaigns, tells Axios Phoenix Sinema would realistically need to get 60,000-65,000 signatures to ensure enough are valid.

• That's possible if the campaign starts in the next two weeks, she says.

1 big number: It would likely cost Sinema's campaign at least $1 million just to qualify for the ballot, Cox says.

• With such an abbreviated timeline, Sinema would be hard-pressed to organize a volunteer operation, meaning she'd have to pay for almost every signature, Cox says.
• She'd almost certainly need to bring in out-of-state paid petition gatherers and cover their lodging during Arizona's peak March visitor season.

Yes, but: Sinema has the money to pull it off with more than $10 million cash on hand. That's about $4 million more than her closest potential competitor, Democratic U.S. Rep. Ruben Gallego.

• However, her fundraising has stalled significantly since she left the Democratic party.
• She most recently reported her worst quarter of the cycle, bringing in less than $600,000, compared with Gallego's $3.3 million and GOP candidate Kari Lake's $2.1 million.

Of note: Sinema's campaign did not respond to our request for comment.

What we're watching: Sinema's challenges don't stop after making the ballot. An Axios Phoenix review found no independent candidates have won state or federal races in the state's history.

• Although independents constitute 34% of Arizona voters — more than registered Democrats and almost equal to Republicans — they don't vote as a monolith in the same way party-aligned voters do.
• Longtime Phoenix politico Chuck Coughlin says independent voters' only guaranteed commonality is they don't want to be a member of a party. They have varying degrees of opinions on all candidates and issues.

The bottom line: "It's very difficult to use them as a base," Coughlin tells us.