The congressional race between GOP Rep. Mia Love and Democratic Salt Lake County Mayor Ben McAdams could not be tighter: It is now tied, according to a new poll.

Each has 46 percent support — with 8 percent undecided — in a survey by the University of Utah’s Hinckley Institute of Politics in partnership with The Salt Lake Tribune.

In the last Tribune-Hinckley poll in June, Love led 45 percent to 39 percent, with 16 percent either undecided or favoring others (even though no other candidates are in the race). Love has attracted few of those previously undecided voters, said Jason Perry, director of the Hinckley Institute.

“But she has not lost a lot of her base support” among Republicans, he said. Meanwhile, McAdams has built support mostly among Democrats and unaffiliated voters, who make up the second biggest voting bloc behind Republicans.

Love is winning Republicans by a 74-15 percent margin, the poll shows. McAdams is carrying nearly all Democratic votes, with a 95-3 percent margin and is leading among unaffiliated voters by a wide 66-26 percent margin.

(Christopher Cherrington | The Salt Lake Tribune)

With voters already casting by-mail ballots, Perry said candidates must move swiftly to focus on the 11 percent of Republicans who are undecided, plus the 8 percent of unaffiliated voters who are.

For McAdams to win, he “needs to spend all of his time focusing on undecided Republicans and unaffiliated voters," Perry said. “Those two categories of voters remain open and up for grabs.”

For Love to prevail, she “needs to be seen in all areas of her district. She needs to be seen knocking on those doors and telling people she wants and needs their vote,” Perry said. “She needs to give them compelling reasons to keep her there by talking about what she has done in office and what she can do for them.”

Both campaigns say they are energized by the new poll’s findings.

“Utahns in the 4th Congressional District are responding to Ben’s proven track record of working across party lines and getting something done on important issues,” said McAdams’ campaign manager, Andrew Roberts.

“He has balanced budgets and brought Republicans, Democrats and independents together to solve challenges. That’s what is driving his candidacy forward, together with the realization that Representative Love has changed and is putting Washington politics ahead of Utah’s interests."

Love herself said she doesn’t believe the poll after her debate with McAdams on Monday night, telling reporters she usually “runs five points ahead of what the Tribune” says, and still expects to win by that much or more.

Dave Hansen, Love’s campaign manager, said, “Right now, it’s all about vote turnout and making sure that the people who are supporting her vote. We feel very confident going into these last three weeks. … We feel we have a plan to get our voters out to the polls.”

He added, “We have seen in our polling that Ben’s unfavorable have skyrocketed once voters have learned about his tax increases and seen his negative campaigning. They do not like the negative attacks that he has been making.”

Actually, both sides have been airing negative ads — with each suggesting in tag lines that the other is untrustworthy.

Perry says that is among the reasons the race is tied.

“This election went negative very quickly. And neither candidate really had a lot of time to build up their policy positions and make their case for voters,” he said. “It almost immediately became each candidate talking about what the other person stood for instead of voters saying, ‘I truly understand their position on issues.’”

Other reasons for the tight race and tie, Perry said, include, “We have two well-known candidates. That doesn’t always happen” — so interest is high.

He also said the 4th District has more Democrats than other congressional districts in Utah, even though it leans GOP. “That makes this a more difficult district for any Republican.”

In short, Perry said, “This is the race to watch in the state of Utah."

The new poll also asked 4th District voters if they approve or disapprove of Love’s performance in office. It found that 49 percent approve, 45 percent disapprove and 6 percent don’t know.

An internal poll by McAdams’ campaign last week said the mayor was leading by 1 percentage point. Narrowing in the race led the Cook Political Report, a respected national elections handicapper, to rate it as a “toss-up."

It is seen as one of the key races nationally that will determine whether Democrats can capture control of the House.