An independent poll shows Republican Rep. Carlos Curbelo with a 1 point lead over Democratic challenger Debbie Mucarsel-Powell—and a contingent of undecided voters large enough to decide the election.

A poll conducted by Mason Dixon Strategies and Telemundo 51 from October 3 to October 9 with 625 registered voters who said they were likely to vote showed a race that is essentially a toss-up for Curbelo’s Miami to Key West congressional seat that President Donald Trump lost more than 16 percentage points two years ago. Curbelo captures 46 percent support while Mucarsel-Powell takes 45 percent. Nine percent of voters are undecided as both campaigns spend millions on TV advertising.

Curbelo once had a lead in the race but Mucarsel-Powell has closed the gap in recent weeks through increased TV spending. Curbelo is better known than Mucarsel-Powell according to the poll and has a higher favorability rating, though Mucarsel-Powell has a lower unfavorable rating than Curbelo. The poll’s margin of error is 4 percentage points, meaning the race is essentially a tie.

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Mason Dixon identified immigration as the most important issue in the district among Hispanic and non-Hispanic voters alike. The economy ranked second while healthcare, the issue that Mucarsel-Powell and Democrats have identified as the most important issue in the district after Curbelo voted to repeal Obamacare, ranks third.

The poll also has potential bad news for Curbelo, who has campaigned on his effort to help draft the GOP’s tax bill last year. Forty-eight percent of voters said they have not benefited from the legislation while 31 percent said they have benefited.

Democrats Bill Nelson and Andrew Gillum also hold a lead in the poll, which only includes voters in the district for races that will be decided by voters across the state. Nelson has a 51 to 43 percent lead over Gov. Rick Scott for his U.S. Senate seat, while Gillum has a 46 percent to 39 percent lead over Republican Ron DeSantis for the open governor’s seat.