Pennsylvania Lt. Governor John Fetterman is running against Republican Dr. Mehmet Oz to succeed Senator Pat Toomey, a Republican who is retiring from the Senate.

Polling analysis paints a mixed picture of a race that could determine which party controls the Senate after the November elections, but Fetterman has enjoyed a lead in recent surveys.

Poll tracker FiveThirtyEight rates the Democrat as “favored” to defeat Oz and gives him 73 chances in 100 of winning the seat, but it’s a different picture in other forecasts.

FiveThirtyEight has produced a polling average of where the candidates stood as of October 5, based upon analysis of recent polls and their own system of pollster ratings.

That analysis found Fetterman leading Oz with 48.7 percent to the Republican’s 42 percent - a lead of more than six points.

A Suffolk University poll for USA TODAY conducted from September 27 to 30 among 500 likely voters found Fetterman leading by a similar margin, with 46 percent to Oz’s 40 percent.

However, the Cook Political Report moved the Pennsylvania Senate race to a “toss-up” this week, two months after it placed the race in the “lean Democratic” column.

The Cook Political Report’s Jessica Taylor said the race was “winnable” for Oz, writing that both parties had admitted that “the race has tightened and that Pennsylvania could be the tipping point for the Senate majority.”

Joe Calvello, the director of communications for Fetterman’s campaign, told Newsweek on Tuesday: “In the past month the GOP threw everything they had at John, they spent millions in negative ads against John, Fox News has attacked John almost every night, but here we are, not only still standing but still winning.”

Larry Sabato’s Crystal Ball forecast at the University of Virginia (UVA) Center for Politics rates the Pennsylvania Senate race as “leans Democrat” and notes that a victory there would be a gain for the party.

Newsweek has asked Fetterman campaign for comment.

Brittany Yanick, communications director with the Oz campaign, told Newsweek in a statement: “John Fetterman is falling behind. Unlike no-show Fetterman, Dr. Oz is talking to voters - Republicans, Democrats, and Independents - who want to see a change from the failed policies of the past. John Fetterman this entire campaign has failed to be honest about two things: his health and his support for releasing convicted murderers back on the streets.

“Dr. Oz is running against the most pro-murderer candidate and we are going to win in November. Pennsylvanians can’t afford another Bernie Sanders socialist that wants to release 1/3 of PA inmates, decriminalize all drugs, and eliminate life sentences for murderers. John Fetterman has already failed to serve the voters of Pennsylvania twice - why would they give him a third chance?.

The contest between Fetterman and Oz is being closely watched, particularly as former President Donald Trump endorsed the celebrity surgeon and the seat is a potential pickup for Democrats, who remain slightly favored to keep control of the Senate, based on FiveThirtyEight’s analysis.

The campaign has been fractious so far, as Oz and Fetterman have repeatedly clashed over the Republican’s long residence in New Jersey, the Democrat’s health following a stroke and other issues.

Fetterman recently described his opponent as “sick” following a report that he had overseen experiments that caused the death of more than 300 dogs as well as other animals.

Update 10/08/22 09.08a.m. E.T.: This article was updated to include a statement from the Oz campaign.