On November 14, 2012, Cornyn was elected Senate Minority Whip by his peers.

Cornyn was named Senate Majority Whip after the 2014 election, in which Republicans gained a Senate majority.


After the death of Associate Supreme Court Justice Antonin Scalia in February 2016, Cornyn said that anyone Obama nominated to replace him would have a difficult confirmation process and feel like a piñata.
He also said that no serious candidate would accept a nomination knowing that they would not be confirmed.
When Obama nominated Merrick Garland to replace Scalia, Cornyn said that even if the president has the constitutional authority to nominate someone, the Senate has full authority on how to proceed.
Cornyn also said that the voice of the people should play a role and that the vacancy should be filled by the winner of the upcoming presidential election, so no hearings on Garland should be held.
The Senate did not vote on Garland's nomination, which expired after the November election of President Donald Trump.
Trump nominated Neil Gorsuch to the seat, and Gorsuch was confirmed.

On June 8, 2017, Cornyn questioned James Comey on Hillary Clinton's emails at a committee hearing whose announced topic was the Russian interference in the 2016 election and Comey's dismissal as FBI director.

In September 2018, during the Supreme Court nomination hearings for Brett Kavanaugh, Cornyn accused the Democrats on the Judiciary Committee of devolving into mob rule by breaking the rules of decorum when asking for postponement or adjournment of the hearing to obtain or review documents from Kavanaugh's time working for the George W. Bush administration.
Cornyn said that it was hard to believe the Democrats' claim that they could not properly assess Kavanaugh without the documents because it seemed that their minds were already made up.

Committee assignments
United States Senate Select Committee on Intelligence
Committee on Finance
Subcommittee on Health Care
Subcommittee on Taxation, IRS Oversight, and Long-Term Growth
Subcommittee on Energy, Natural Resources, and Infrastructure
Committee on the Judiciary
Subcommittee on Antitrust, Competition Policy and Consumer Rights
Subcommittee on the Constitution
Subcommittee on Immigration, Refugees and Border Security (Chairman)
Subcommittee on Terrorism, Technology and Homeland Security
On November 14, 2012, Cornyn was elected Senate Minority Whip by his peers.
Cornyn was named Senate Majority Whip after the 2014 election, in which Republicans gained a Senate majority.

After the death of Associate Supreme Court Justice Antonin Scalia in February 2016, Cornyn said that anyone Obama nominated to replace him would have a difficult confirmation process and feel like a piñata. He also said that no serious candidate would accept a nomination knowing that they would not be confirmed. When Obama nominated Merrick Garland to replace Scalia, Cornyn said that even if the president has the constitutional authority to nominate someone, the Senate has full authority on how to proceed. Cornyn also said that the voice of the people should play a role and that the vacancy should be filled by the winner of the upcoming presidential election, so no hearings on Garland should be held. The Senate did not vote on Garland's nomination, which expired after the November election of President Donald Trump. Trump nominated Neil Gorsuch to the seat, and Gorsuch was confirmed.
On June 8, 2017, Cornyn questioned James Comey on Hillary Clinton's emails at a committee hearing whose announced topic was the Russian interference in the 2016 election and Comey's dismissal as FBI director.
In September 2018, during the Supreme Court nomination hearings for Brett Kavanaugh, Cornyn accused the Democrats on the Judiciary Committee of devolving into mob rule by breaking the rules of decorum when asking for postponement or adjournment of the hearing to obtain or review documents from Kavanaugh's time working for the George W. Bush administration. Cornyn said that it was hard to believe the Democrats' claim that they could not properly assess Kavanaugh without the documents because it seemed that their minds were already made up.
Committee assignments
United States Senate Select Committee on Intelligence
Committee on Finance
Subcommittee on Health Care
Subcommittee on Taxation, IRS Oversight, and Long-Term Growth
Subcommittee on Energy, Natural Resources, and Infrastructure
Committee on the Judiciary
Subcommittee on Antitrust, Competition Policy and Consumer Rights
Subcommittee on the Constitution
Subcommittee on Immigration, Refugees and Border Security (Chairman)
Subcommittee on Terrorism, Technology and Homeland Security
John Cornyn