Chicago Mayor Rahm Emanuel is widening his lead over Cook County Commissioner Jesús "Chuy" García ahead of the city's April 7 mayoral runoff election that was forced when Emanuel didn’t surpass the 50 percent threshold in the general election last month, according to a survey released Sunday. Emanuel now has about a 9-percentage-point lead compared with a lead of about 7 percent in a poll taken last week.

Emanuel’s massive campaign war chest compared with García’s has partly contributed to the Chicago mayor’s rising poll numbers, because those funds are being used to pay for attack ads against García that are shown to be working, according to Ogden & Fry, the firm that conducted the poll. Emanuel was at 47 percent in the latest poll, while a little more than 36 percent said they will vote for García in the runoff. About 16 percent of voters are undecided.       

“Despite an impressive rollout of high-profile endorsements for García, Emanuel has opened a lead on García,” Ogden & Fry said in a statement. “Emanuel’s financial advantage is starting to have an effect with his TV commercials.”

Although Emanuel has improved his lead, García, who is a native of Mexico and is viewed as the progressive candidate in the race, can close the gap with undecided voters, who are not likely to vote for the Chicago mayor, according to Ogden & Fry. Polls are also known to under-represent Latino voters, so García’s support may be understated.

“Conventional wisdom is that undecideds usually do not break for a well-known incumbent,” Ogden & Fry said. “García seems to hold around a 6% (53%-47%) advantage with the undecided voters at this point.”

From the first post-general election poll in late February to Sunday’s survey, Emanuel has seen his lead rise in Ogden & Fry polling from 4 points to 9. Last week’s poll had Emanuel at 43.5 percent to García’s 38 percent with 18 percent undecided.

The latest poll surveyed 957 likely voters and was conducted Saturday. It has a margin of error of plus- or minus-3.23 percentage points.