Tenure
On November 15, 2010, Coons was sworn in as Delaware's newest senator by Vice President Joe Biden, the former occupant of Coons's Senate seat. Joe Manchin of West Virginia was sworn in on the same day, though he took an advantage in seniority over Coons, as the former governor of West Virginia.
The Affordable Care Act (commonly called Obamacare) had already been passed when Coons took office, but he has voted against repealing it, emphasizing that seniors in Delaware would have to pay higher prescription drug prices if it was repealed. In September 2017, Coons said the Graham-Cassidy bill, meant to replace the Affordable Care Act, would be playing "Russian roulette with the American health care system."
On abortion, Coons has received a 100% rating from the Planned Parenthood Action Fund and a 0% rating from the National Right to Life Committee.
In June 2013, after the death of Democratic senator Frank Lautenberg of New Jersey, Coons was appointed to his seat on the influential Appropriations Committee, becoming the first senator from Delaware to serve on the committee in 40 years. As a result, he gave up his seat on the Committee on Energy and Natural Resources.
In October 2013, Coons announced the formation of the inaugural Senate Chicken Caucus in the United States Senate. He stated, "I hope that the Senate Chicken Caucus will give America's chicken producers a platform to better inform legislators about the industry's vital contributions to our economy, and promote policy solutions that help their businesses grow and thrive."
On December 11, 2013, Coons introduced the Victims of Child Abuse Act Reauthorization Act of 2013 (S. 1799; 113th Congress), a bill that would reauthorize the Victims of Child Abuse Act of 1990 and would authorize funding through 2018 to help child abuse victims. Coons said that "we have a responsibility to protect our children from violence and abuse."
In March 2014, Coons voted against President Obama's nomination of civil rights lawyer Debo Adegbile for Assistant Attorney General for Civil Rights, even though he believed that Adegbile would have been "an asset to the Justice Department." He stated that voting for a nominee "who would face such visceral opposition from law enforcement on his first day on the job" was troubling and the vote was "one of the most difficult I have taken since joining the Senate". Obama described the Senate's vote against Adegbile as "a travesty based on wildly unfair character attacks against a good and qualified public servant." An open letter to Coons from students, faculty and alumni of the Yale Law and Divinity Schools, of which Coons is an alumnus, criticized his vote as "alarm[ing]" and "signal[ing] a lack of respect for the fundamental American legal principle that all parties have a right to zealous representation."
Coons was mentioned as a possible replacement for the late Justice Antonin Scalia in February 2016.
In April 2017, after President Trump tweeted that North Korea had "disrespected the wishes of China & its highly respected President" with a recent missile launch, Coons said Trump understood China was his sole "constructive path forward on North Korea" but that diplomacy would not work through tweeting.
In July 2017, Coons voted in favor of the Countering America's Adversaries Through Sanctions Act that placed sanctions on Iran together with Russia and North Korea.
In April 2018, following the FBI raid on the hotel room and offices of Trump's personal attorney, Michael Cohen, Coons, Cory Booker, Lindsey Graham, and Thom Tillis introduced new legislation to "limit President Trump's ability to fire special counsel Robert Mueller". Termed the Special Counsel Independence and Integrity Act, the legislation would allow any special counsel, in this case Mueller, to receive an "expedited judicial review" in the 10 days following being dismissed to determine whether the dismissal was appropriate. If not, the special counsel would be reinstated. At the same time, according to The Hill, the bill would "codify regulations" that a special counsel could be fired only by a senior Justice Department official, while having to provide reasons in writing.
In November 2020, Coons was named a candidate for Secretary of State in the Biden administration. Biden ultimately chose Antony Blinken to lead the State Department, telling Coons, "I need you in the Senate." Coons was seen as among Biden's closest allies in the Senate, and co-chaired Biden's 2024 reelection campaign.
During the 2021 attack on the United States Capitol, Coons was evacuated from the Senate chambers, along with other senators and staff. He said there were "some scary and chaotic moments" during the attack. When the Senate reconvened to certify the Electoral College vote count, Coons called for Trump's removal, saying he "poses a real and present threat to the future of our democracy". He called for the invocation of the Twenty-Fifth Amendment to the United States Constitution the day after the event on Good Morning America. That same day, January 7, he called for Republicans Josh Hawley and Ted Cruz, who both challenged the election results, to resign from the Senate.
In November 2025, following disclosures that the FBI's Arctic Frost investigation had obtained phone records of Republican senators without notification, Coons expressed concern about the surveillance of legislators, saying, "On the surface of it, it would strike me as a significant invasion of the right of senators to conduct their jobs, so this is something that needs urgent follow-up." Coons also co-sponsored the Anti-Cash Grab Act, legislation introduced by Senators Martin Heinrich and Mark Kelly to repeal a provision in the government funding bill that allowed senators to sue for $500,000 in damages over seized phone records.
Coons, Senator Tom Carper, and President Biden declined to select a nominee for a judicial vacancy on the Third Circuit in Biden's home state of Delaware even though the vacancy was announced in May 2024, more than eight months before Biden's term in office ended. The White House's and the Delaware U.S. Senate delegation's decision not to fill the vacancy, along with Biden's unsuccessful nomination of Adeel A. Mangi to another Third Circuit vacancy, allowed President Trump to fill both seats in 2025 and give the Third Circuit a conservative majority. Trump nominated Jennifer Mascott, who had never taken the Delaware bar exam and was not licensed to practice law in Delaware.
