PHOENIX - Democratic Rep. Kyrsten Sinema has a lead over her Republican rivals for the Senate seat being vacated by Sen. Jeff Flake, a NBC News-Marist poll shows.

The poll, released Tuesday, says Sinema is favored among registered voters over Joe Arpaio, Martha McSally and Kelli Ward.

Sinema vs. Arpaio

Krysten Sinema — 57%
Joe Arpaio — 32%
Other — 2%
Undecided — 9%

Sinema vs. McSally

Krysten Sinema — 49%
Martha McSally — 38%
Other — 2%
Undecided — 11%

Sinema vs. Ward

Krysten Sinema — 48%
Kelli Ward— 38%
Other — 2%
Undecided — 12%

These numbers were gathered by surveying 839 registered Arizona voters between June 17 and 21. The poll has an overall margin of error of 4.5 percentage points.

Sinema, the Democratic front-runner, represents Arizona's ninth district in Congress, a district that includes Tempe and other parts of Maricopa County. In her primary, she's running against attorney and community activist Deedra Abboud who made headlines last year when she received hateful attacks on her Facebook page for being Muslim.

While Sinema has an 11-point lead over her, McSally is the front-runner in the Republican race. The poll asked 371 potential Republican voters which Republican candidate they prefer. McSally narrowly leads Ward, 30 percent to 28 percent, while 21 percent of those surveyed support Arpaio. The poll has a 6.7 percentage point margin of error.

RELATED: I asked Joe Arpaio basic questions for a U.S. Senate candidate. It didn't go well.

Arizona's primary will take place Aug. 28.

The poll also asked Arizona voters if Gov. Doug Ducey should be reelected and 59 percent of them said they want someone new to lead the state. Only 26 percent of voters said Ducey should serve another term and 15 percent said they were unsure.

The NBC-Marist poll was also conducted in Ohio and Florida where Democrats are leading in those Senate races as well.