Democrat Kirsten Engel is up by 1.7 percentage points over incumbent Republican U.S. Rep. Juan Ciscomani in their rematch in Arizona's Congressional District 6.
Engel has 49.8% of the vote to Ciscomani's 48.1%, a lead of just 4,664 votes.
Engel's lead shrunk as some Cochise County results came in after 10 p.m. in the swing district, which includes voters in several counties including Pima and Pinal.
Ciscomani Engel for the U.S. House seat two years ago by just over 5,000 votes. He was an aide to Republican former Gov. Doug Ducey.
Engel is a University of Arizona law professor and a former state legislator.