If he is elected to a second term, President Biden pledged that he will go to Congress to start any major war but said he believed he was empowered “to direct limited U.S. military operations abroad” without such approval when such strikes served critical American interests.
“As president, I have taken great care to ensure that military actions carried out under my command comply with this constitutional framework and that my administration consults with Congress to the greatest extent possible,” he wrote in response to a New York Times survey of presidential candidates about executive power.
“I will continue to rigorously apply this framework to any potential actions in the future,” he added.
The reply stood in contrast to his answer in 2007, when he was also running for president and, as a senator, adopted a narrower view: “The Constitution is clear: Except in response to an attack or the imminent threat of attack, only Congress may authorize war and the use of force.”
In the survey, The New York Times asked major presidential candidates to lay out their understanding of issues that can be critical to the outcome of policy fights but about which they are rarely asked: the scope and limits of a president’s power to act unilaterally or in defiance of statutes, particularly in war, secrecy and law enforcement.
Mr. Biden’s answers showed how his view of executive power evolved over years in the White House — eight as Barack Obama’s vice president and now nearly three as president.
Only a handful of candidates for the Republican nomination engaged in the survey, including former Vice President Mike Pence, former Gov. Asa Hutchinson of Arkansas and Mayor Francis Suarez of Miami before he suspended his campaign late last month.
Vivek Ramaswamy, a businessman and entrepreneur, answered only about half of the 14 questions, and former President Donald J. Trump declined to participate altogether, as did Gov. Ron DeSantis of Florida and Nikki Haley, the former ambassador to the United Nations, among others.
The Times has published in full the answers of participants, including Mr. Biden and two of his Democratic challengers, Robert F. Kennedy Jr. and Marianne Williamson.
Notably, Mr. Biden declined to embrace the idea of curtailing emergency powers Congress enacted that presidents can activate if they declare that there are exigent circumstances, said Jack Goldsmith, a Harvard Law School professor and former senior Justice Department lawyer in the Bush administration.
Mr. Trump invoked emergency powers to spend more on a border wall than lawmakers were willing to appropriate, and the Biden administration invoked the authority for a plan to forgive more than $400 billion in student debt. (The Supreme Court struck down the proposal over the summer.) There are bipartisan proposals in Congress to impose new curbs, such as by ensuring that national emergencies terminate after 30 days unless lawmakers affirm a presidential declaration.
Asked whether he would sign such a bill, Mr. Biden instead made a vague remark about “working with Congress on devising sensible solutions to the challenges we face as a nation.” He added that he would use every tool at his disposal to respond to emergencies.
“If Biden is not open to reform — and his answer was as noncommittal as he could be without saying he was not open to it — then it is likely dead on arrival,” Professor Goldsmith said.
On the topic of pardons, every candidate who answered the survey said that a president cannot pardon himself. While in office, Mr. Trump claimed he had a legal right to do so, but that is an ambiguous and untested constitutional question. It could become important if he wins the 2024 election even as he faces criminal charges in two federal cases.
Indeed, while Mr. Trump did not participate in the survey, many of its questions addressed disputed assertions of executive power he made as president, and he and his allies are openly planning to expand his authority over the machinery of government if he wins in 2024. Mr. DeSantis has also pushed an expansive view of executive powers as Florida governor.
The refusal by the two men and most other G.O.P. contenders to answer questions on the powers they are seeking from voters reflects a party shift that emerged in the 2016 primary, which Mr. Trump upended by becoming the front-runner ahead of establishment candidates.
Other Republican presidential hopefuls in the current primary campaign who declined to answer the questions included Senator Tim Scott of South Carolina, Chris Christie, the former governor of New Jersey, Gov. Doug Burgum of North Dakota, and Will Hurd, a former representative of Texas.
By contrast, most major Republican primary candidates in 2007 and 2011 were willing to answer the versions of the questions put to them those years, including the party’s eventual nominees, John McCain and Mitt Romney.
Four years ago, 17 Democrats vying for their party’s nomination to challenge Mr. Trump also participated in the project. Mr. Biden was among them, making his answers this cycle the third time he has participated. (His willingness to do so as an incumbent seeking re-election also stood in contrast to Mr. Obama, who declined to participate in 2011.)
In 2019, Mr. Biden had already shifted to embracing the view, adopted by the executive branch under administrations of both parties, that presidents have broader constitutional authority to carry out limited attacks on other countries without congressional authorization, so long as it falls short of full-scale war.
As president, both Mr. Trump and Mr. Biden used force unilaterally, citing their claimed constitutional authority to use military force without congressional permission. In April 2017 and again in April 2018, Mr. Trump directed airstrikes against Syrian government forces, and Mr. Biden in June 2021 and in August 2022 directed airstrikes on Iranian-backed militia groups in Syria.
Mr. Pence, who was vice president at the time of Mr. Trump’s strikes, said: “As commander in chief, the president has a constitutional duty to use his executive authority to protect the country from imminent threats. Whether a threat is imminent is a matter of judgment, and it is essential the president be a person of character, experience, and competence whose judgment the American people can trust.”
To be sure, just because candidates commit to respecting a limit while on the campaign trail does not mean they will follow through once in office. But their legal policy statements can offer a way to analyze and bring attention to any departure from what they told voters.
In 2019, for example, Mr. Biden said that if elected, he would order the Justice Department to review and potentially replace a legal policy memo that says sitting presidents are temporarily immune from indictment. He strongly criticized the department’s interpretation of the Constitution, which limited the special counsel investigating the Trump campaign’s ties to Russia and Mr. Trump’s attempts to impede that inquiry, Robert S. Mueller III.
But Mr. Biden never followed through on that pledge. He is now protected himself by the Justice Department’s theory since a special counsel, Robert Hur, is investigating how several classified documents were in his possession when he left the vice presidency.
In his survey answers this time, Mr. Biden sidestepped a question about that issue, instead offering a vague statement about Justice Department independence.
“As president, I have fulfilled my campaign promise of restoring a strong and independent Department of Justice led by top-flight legal professionals dedicated to realizing the ideal that this nation was founded on of equal justice under the law,” he wrote. “This means no one is above the law — especially the president of the United States.”