In San Diego County’s most closely watched congressional race, three-term Democratic incumbent Rep. Mike Levin holds a 13-point lead over Republican challenger Matt Gunderson, a new San Diego Union-Tribune poll finds — despite recent indicators the North County race could be tightening. That’s similar to the 12-point lead the three-term Democrat held over the Republican car dealer in another poll earlier this month, although both men command a slightly lower percentage of support overall as the share of undecided or nonparticipating voters rose. And it’s wider than the margins by which Vice President Kamala Harris leads former President Donald Trump, and by which Rep. Adam Schiff leads Steve Garvey for Senate, within the district. According to the new poll from SurveyUSA for the Union-Tribune and Channel 10 News, 51% of respondents were voting for Levin, compared with 38% for Gunderson. Another 8% said they were undecided and 3% were not voting. The poll was conducted Oct. 25 to 31 by a combination of landline telephone and onscreen digital survey. The respondent pool was weighted to demographic targets, and the poll had a credibility interval of roughly 5 percentage points. Levin has the support of 53% of those voters who said they were not registered as either a Democrat or a Republican, while Gunderson has the support of 37%. Few voters who now support a congressional candidate appear to be wavering — 87% of those polled said they were certain of their vote, and 80% percent said it was very important to vote in the race. Voters’ top issues may be driving that certainty, particularly as the candidates and their parties focus heavily on those issues. Eighty-eight percent of voters whose top issue is climate change support Levin, along with 91% of those whose top issue is abortion. Gunderson has recently sought to defend his position on abortion, calling himself both “pro-choice” and “a states’ rights guy.” By contrast, 73% of those who say the top issue is immigration back Gunderson, according to the new poll. Voters whose top issues are the economy or foreign policy are more split. But Gunderson leads by 16 points among those who cite the economy —as 40% of those polled do. The 49th Congressional District stretches from Del Mar north through Oceanside, Vista and Camp Pendleton into southern Orange County and for years has been San Diego County’s most competitive. As of last month, its electorate was about 36% registered Democrats, 34% Republicans and 21% voters with no party preference; the remainder were registered with other political parties. Per the new poll, Harris leads in the presidential race among the district’s voters by 52% to Trump’s 44%. Schiff’s lead for California’s open Senate seat is slimmer — 47% to 41% for Garvey. The district has long been regarded as a battleground district, and was seen in 2022 as crucial to Democrats’ hopes in the House. The widely respected Cook Political Report recently downgraded Levin’s advantage there — it’s now ranked as “lean” Democratic rather than the more comfortable designation of “likely” Democratic.