UPDATE 3:35 p.m. ET: A second poll released Monday indicates a much wider gap in the race, with Booker ahead by 22 points, 58%-36%.
(CNN) - The gap between Democratic nominee Cory Booker and Republican nominee Steve Lonegan is shrinking, but Booker still holds onto the lead in the New Jersey special Senate race, according to a poll released Monday, two days before Election Day.
The new Monmouth University survey indicates 52% of likely voters back Booker, while 42% support Lonegan, and four percent undecided.
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The poll was conducted Thursday through Saturday, mostly before Lonegan held a high-profile rally where former Alaska Gov. Sarah Palin turned out to show her support. Meanwhile, Booker, the mayor of Newark, canceled campaign events Thursday and Friday after the death of his father.
Respondents were questioned entirely after the two candidates faced off Wednesday in their final debate, a showdown marked by piercing attacks that focused on everything from their stances on same-sex marriage to the ongoing partial government shutdown.
Lonegan, former mayor of the northern New Jersey town of Bogota, has tried to paint Booker as nothing but a celebrity, while Booker tries to characterize Lonegan as a far-right, tea party conservative.
The new survey's 10 percentage point gap is slimmer than polls in recent weeks, when the margin hovered between 12%-16%.
Booker's campaign released a video message Monday from President Barack Obama, who urged New Jersey voters to turn out for the Democratic candidate.
"Cory Booker has spent his entire life bringing people with different perspectives together, regardless of party, to take on tough challenges," he said.
Lonegan's campaign attacked Booker's relationship with Obama last week in a television ad, calling Booker an "Obama rubber stamp."
While each candidate carries his respective party, Lonegan has a narrow advantage among independents, 48% to 43%, whereas Booker had the lead among independents two weeks ago, according to Monmouth.
A total of 12% of likely voters in the new poll say they're either undecided or could change their mind, two days before Election Day. When looking at voters who have made up their mind, Booker's advantage narrows slightly, 47% to 39%.
"Concerns about Cory Booker's intentions to serve New Jersey continue to persist and his favorability ratings continue to drop. At the same time, voters clearly prefer Booker's political views over Lonegan's. The message seems to be that Garden State voters don't like to feel that their support is being taken for granted," said Patrick Murray, director of the Monmouth University Polling Institute, in a release about the survey.
Booker's favorability ratings have declined, though he still has a positive margin, with 51% saying they have a favorable view of the mayor, while 30% say they hold an unfavorable view. In June, his ratings stood at 61% favorable to 15% unfavorable, according to Monmouth polling.
Lonegan's favorability has also declined, with 38% of likely voters holding a favorable view of the Republican, compared to 35% who don't view him in a favorable light. The three point positive gap is smaller than the positive 14 point gap he had in June.
With the election being held on a Wednesday, just weeks before the state's gubernatorial election, questions persist over voter turnout. According to Monmouth's voter model, 35%-40% of registered voters will show up at the polls.
Monmouth questioned 1,393 likely voters in New Jersey by telephone from October 10-12. The overall sampling error is plus or minus 2.6 percentage points.
- CNN's Jason Seher contributed to this report.