Sen. Bob Casey, D-Pa., has decided not to run for president in 2020, saying in a statement that the best way for him to fight for America is to remain in the Senate.

“After two months of considering it, I have concluded that the best way for me to fight for the America that so many of us believe in is to stay in the U.S. Senate and not run for the presidency in 2020,” Casey said in a statement.

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Casey, who won a third Senate term in November, said that he has been considering a run because Pennsylvania could potentially play a key role in 2020. Trump’s narrow wins in Pennsylvania, Michigan and Wisconsin were central to his victory in 2016, and will be key states next year.

Casey said that instead of running for the White House, he had decided that he wants to build on achievements in his time in office.

“Pennsylvania workers need a Senator who will always fight for their economic livelihoods, and our children and seniors need a Senator who puts their needs first. I will also continue to fight for the goals of the Americans with Disabilities Act: full participation, independent living, equal opportunity and economic self-sufficiency,” he said.

Casey said that he is sure that Democrats will pick a candidate who can win the state.

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“2020 is not the time for me to run for President, but it is the right time for me to continue to fight the battles I have fought as U.S. Senator and state official,” he said in his statement. “I have no doubt that our Democratic Party will nominate a candidate who can win Pennsylvania and the Presidency.”

Democratic 2020 hopefuls are likely to face a packed field. Candidates including Sen. Elizabeth Warren, D-N.Y., Rep. Tulsi Gabbard, D-Hawaii, Sen. Kirsten Gillibrand, D-N.Y., and former HUD Secretary Julian Castro have all thrown their hats into the ring, and a number of other names, including Sens. Cory Booker, D-N.J., Kamala Harris, D-Calif., and former Vice President Joe Biden, are all believed to be considering bids.

Fox News' Patrick Ward contributed to this report.