Democrats determined to win the Arizona Senate race breathed a sigh of relief this week when Sen. Kyrsten Sinema (R-Az.) revealed that she would not run for re-election.

Why it matters: Sources in and around the campaign of Democrat Ruben Gallego told Axios that Sinema's departure was a welcomed development and simplifies his path to victory over Republican Kari Lake.

• Sinema, a former Democrat who left the party in 2022, was pulling support from more Republicans than Democrats in polling of the race.
• Several Democratic sources told Axios they are confident Lake, the Trump-aligned bomb thrower, will not win back the support of moderate Republicans and independents they say she has alienated.
• Republicans argue they are more comfortable in a head-to-head race with Gallego.

The big picture: Democrats were quick to rally around Gallego after Sinema revealed that she would not seek reelection.

• Sen. Mark Kellly (D-Az.) told Axios that "Ruben is going to beat Kari Lake and he is going to be an effective member of our caucus."
• Sen. Gary Peters (D-Mich.), who chairs the campaign arms of Senate Democrats, told Axios "we were gonna win regardless, but now we even have a stronger hand."

By the numbers: Recent internal Republican polling showed Sinema was pulling two times more support from Lake than Gallego, a national GOP strategist told Axios.

• A source close to the Gallego campaign argued that in the home state of the late Sen. John McCain (R-Ariz.), those moderates and independents who were throwing their support behind Sinema will not jump to Lake.
• "Recent public polling, and even Republicans' own internal polling, has shown a two-candidate race is better for Democrats and Gallego," a national Democratic strategist working on Senate campaigns told Axios.

Between the lines: Lake aggressively pushed the false claim that the 2020 election was stolen from former President Trump and that her gubernatorial campaign that year was rigged.

• Lake said to reporters during a visit to the U.S. Capitol on Tuesday that "we had a really rigged election in Arizona."
• Democrats are hoping that type of rhetoric has made Lake a nonstarter for moderate Republicans and independents.

The other side: Republicans insist having the race be a clear choice between Lake and Gallego is what they wanted.

• "We're more comfortable in a two-way race because it's more predictable and Gallego is much further left than Sinema or Mark Kelly," the national GOP strategist said.