Rep. Charles Rangel of New York leads his challenger, State Sen. Adriano Espaillat, 47 percentage points to 34 points ahead of the Democratic primary on Tuesday, according to a NY1/Siena College poll.
Rangel, who has represented the district in Congress for 22 terms, has seen his lead among likely voters jump to 13 points from a 9-point lead in last month's Siena poll.
Voters believe, by a nearly two-to-one margin, that Rangel, 84, will emerge victorious in the district, which includes Harlem and parts of the Bronx, the poll released on Thursday found.
In that liberal bastion, the winner of the Democratic primary is all but guaranteed to win the general election in November.
The race is a re-match. In 2012, Rangel defeated Espaillat by fewer than 1,000 votes.
The poll found voters divided along racial lines.
Rangel, who is black, holds a 70-point advantage among blacks while Espaillat, who grew up in the Dominican Republic, holds a 24-point advantage among Latinos. White voters in the district favor Rangel 43 percent to 38 percent.
Rangel's backers were also more committed to their candidate.
More than seven in 10 Rangel supporters say they are certain to vote for Rangel, while more than six in 10 Espaillat supporters say that there is no chance they will change their minds, the poll found.
And voters believe by a nearly two-to-one margin that Rangel, who was censured by the House in 2010 after an ethics scandal, will emerge victorious.
"With less than a week until voters go to the polls, the long-time incumbent appears to be holding off the challenger," said Siena College pollster Steven Greenberg.
The telephone poll of likely Democratic voters was conducted from June 14 to June 18 and had a margin of error of plus or minus 3.7 percentage points.
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