The president tends to shoot from the hip, while Secretary of State Rex W. Tillerson is more plodding, which has won him few friends in Washington.
The president is expected to declare that the two-year-old Obama-era approach of engagement had amounted to a failed policy of appeasement.
The Senate overwhelmingly approved a proposal aimed at punishing Russia for its meddling in the 2016 election. The House has yet to take it up.
Senate leaders said they had reached an agreement to approve the new sanctions, which would place the White House in an uncomfortable position.
The resignation came after it was revealed that Mr. Flynn had misled Vice President Mike Pence and other top White House officials about his conversations with the Russian ambassador to the United States, according to a person close to the administration.