Tenure
On February 12, 1999, Crapo was one of 50 senators to vote to convict of impeachable offenses and to remove Bill Clinton from office.
In the 111th Congress, Crapo served on the following Senate committees: Banking, Housing and Urban Development; Budget; Environment and Public Works; Indian Affairs; and Finance. He co-chairs the Senate Nuclear Caucus, the Canada-U.S. Inter-parliamentary Group (IPG); the COPD (Chronic Obstructive Pulmonary Disease) Caucus, which he founded; and the Congressional Sportsmen's Caucus.
Crapo became the state's senior senator when the 111th United States Congress convened on January 3, 2009, succeeding Larry Craig, who decided not to seek reelection. At the convening of the 112th United States Congress, Crapo ranked 39th in seniority in the Senate.
He opposed President Barack Obama's health reform legislation, voted against the Patient Protection and Affordable Care Act in December 2009, and voted against the Health Care and Education Reconciliation Act of 2010.
In April 2013, Crapo was one of 46 senators to vote against a bill that would have expanded background checks for all gun buyers. He voted with 40 Republicans and 5 Democrats to stop passage of the bill.
The New York Times noted that Crapo became "something of a hero among advocates of bipartisanship" for his involvement in the "Gang of Six".
In 2017, Crapo was one of 22 senators to sign a letter to President Donald Trump urging him to withdraw the United States from the Paris Agreement.
Crapo's view on senatorial responsibilities for Supreme Court nominees has evolved. Of President George W. Bush's 2006 nomination of Samuel Alito, Crapo said in a press release, "All of the President's nominees deserve up-and-down votes and not efforts to obstruct judicial nominees for political purposes. Judges are not politicians, and hopefully, Judge Alito's nomination will put an end to the politics which have crept into the nomination process." By contrast, in 2016, his press release regarding President Obama's nomination of Merrick Garland to replace the late Antonin Scalia said:
The Constitution gives the President the right to make nominations to the Supreme Court, with the advice and consent of the Senate. As part of its role in this process, the Senate may, at its discretion, withhold consent. The next Supreme Court justice will make decisions that affect every American and shape our nation's legal landscape for decades. Therefore, the current Supreme Court vacancy should be filled by an individual nominated by the next President of the United States.
In September 2020, with less than two months to the next presidential election, Crapo voiced support for an immediate Senate vote on Trump's nominee to fill the Supreme Court vacancy caused by the death of justice Ruth Bader Ginsburg, once a "well-qualified candidate" was put forth.
For his tenure as the chairman of the Senate Banking, Housing, and Urban Affairs Committee during the 116th Congress, Crapo was given an "F" grade from the non-partisan Lugar Center's Congressional Oversight Hearing Index.
On January 6, 2021, Crapo was participating in the certification of the 2021 United States Electoral College vote count when Trump supporters attacked the United States Capitol. In response, he called for "perpetrators" to be "prosecuted to the fullest extent of the law". He opposed removing Trump from office, saying that the "country is too divided" and that invoking the Twenty-fifth Amendment to the United States Constitution "would only make matters worse".
Crapo has served as the chair of the Senate Republicans's Committee on Committees since 2003, which coordinates the committee assignments for the caucus as a whole.
In October 2023, Crapo visited China as part of a bipartisan congressional delegation led by Senate Majority Leader Chuck Schumer and met with General Secretary of the Chinese Communist Party Xi Jinping. Crapo said he would raise concerns about market-access on behalf of Micron Technology, which faced restrictions in China. The delegation also met Director of the Office of the Central Foreign Affairs Commission Wang Yi, Chairman of the Standing Committee of the National People's Congress Zhao Leji, and Shanghai Communist Party Secretary Chen Jining.
In September 2025, Crapo chaired a heated three-hour Senate hearing with Robert F. Kennedy Jr. Crapo denied Ron Wyden's request to have Kennedy formally sworn in as a witness.
