The new poll released on Monday shows Democratic candidates in Pennsylvania, Arizona and Georgia poised to win against their Republican challengers, as well as a highly competitive contest in a fourth Senate race.

Incumbent senators Mark Kelly of Arizona and Raphael Warnock of Georgia both lead their GOP opponents, Blake Masters and Herschel Walker, at 54 to 51 percent and 49 to 46 percent, respectively. Pennsylvania’s Democratic candidate John Fetterman was also shown leading 49 to 44 percent over Republican Mehmet Oz, although the survey was conducted before the Keystone State’s testy debate last week.

In Nevada, Senator Catherine Cortez Masto is neck-and-neck with Republican rival Adam Laxalt, tied at 47 percent. As of Monday, FiveThirtyEight shows the incumbent Democrat with the slight advantage of 0.4 points.

As of Monday afternoon, the election forecaster is predicting a “dead heat” for the Senate, with Democrats having a 51-in-100 chance of keeping control of the chamber.

Although Democrats appeared to have the advantage in Monday’s survey, pollsters found that more respondents preferred a Republican-controlled Senate, suggesting that candidate quality worked in favor of the Democratic Party.

However, the Times’ chief political analyst Nate Cohn noted that, “As we head down the stretch, Republicans can hope to lure some of these voters to their side.”

Republicans would only need to flip one seat to take control of the Senate. Although the move could be successfully executed by Laxalt in Nevada, a victory by Fetterman in Pennsylvania—where candidates are fighting to win an open seat left by Republican Senator Pat Toomey—could be enough to offset a GOP win. But a loss in both states would hand the Senate over to Republicans.

While Monday’s poll showed Fetterman with a 6-point lead, other pollsters show a tighter race between the Democrat and Oz. Just shy of a week before Election Day, FiveThirtyEight has Fetterman with a 1-point advantage, down 10 points from the nearly 11-point lead he had in September.

Last week’s sole Senate debate in Pennsylvania appeared to help Oz narrow the gap, which was 2.6 points last Monday. During the debate, lingering stroke effects took their toll on Fetterman, who struggled at times to respond to the moderators’ questions.

FiveThirtyEight’s current polling averages also show Kelly and Warnock ahead in Arizona and Georgia, although by smaller leads.