WASHINGTON — Some senior Trump administration officials are pressing for more aggressive action toward Russia, hoping to persuade a reluctant President Trump to change his approach after a week of mass diplomatic expulsions that have driven the relationship with Moscow to its lowest point in decades.

With hundreds of diplomats in Washington, Moscow and European capitals packing their bags as the tensions stemming from the poisoning of a former Russian spy living in Britain have worsened, the Trump team is eyeing additional sanctions and other measures against Russia. But while aides say the president has become increasingly convinced that Russia is dangerous, he has still refused to embrace a tougher public posture himself and remains uncertain how far to authorize his administration to go.

Mr. Trump has emphasized the importance of dialogue with Russia and its president, Vladimir V. Putin, yet the departure of so many diplomats expelled from both Russia and the United States will make it that much harder to maintain a semblance of normal relations between the two countries. Cooperation in areas as varied as agriculture, counterterrorism, military affairs and space exploration could diminish, as could private travel and business dealings.

The perils of the diplomatic breakdown came into sharper relief on Friday. Russia’s ambassador in Washington lamented that no one would meet with him, and his embassy complained that Russian diplomats were being harassed by American intelligence agencies eager to recruit them.