Pennsylvania Sen. Bob Casey (D) is leading by 9 points in his Senate reelection bid against Republican challenger David McCormick, a new survey found.

The University of Massachusetts Lowell/YouGov poll found Casey earning 48 percent support among likely voters, while McCormick trails at 39 percent. About 10 percent say they are undecided.

The survey found independents favor Casey, who earns 37 percent support among independent Pennsylvania voters to McCormick's 26 percent.

McCormick is more popular among voters aged 45-64, while Casey has the most support among younger and older voters.

Most voters who plan to cast their ballot for Casey or McCormick say they won’t change their mind. Only 12 percent say they could change their mind about voting for Casey before Election Day, and 15 percent say the same about McCormick.

The Pennsylvania Senate race is going to be one of the most closely watched races for the upper chamber this year. Democrats are looking to hold their majority in the Senate and keep Republicans from seizing control.

According to The Hill/Decision Desk HQ polling average, Casey has a 3.6 percentage point lead over McCormick. The Democrat has 48.3 percent support compared to the Republican’s 44.7 percent.

Pennsylvania will be one of the tightest races in the presidential election, too. Vice President Harris and former President Trump are looking to secure the state’s 19 electoral votes. Harris leads Trump by 0.3 percentage points in the state, with 48.6 percent support compared to his 48.3 percent, according to The Hill/Decision Desk HQ average.

The survey was conducted Oct. 2-9 among 800 Pennsylvania likely voters and has a margin of error of 3.97 percentage points.