The US will seek to clarify Turkey's opposition to Sweden and Finland joining NATO at a meeting this weekend.
Turkish President Recep Tayyip Erdogan said on Friday that his country is "not favourable" towards the Nordic nations joining NATO, indicating Turkey could use its membership in the western military alliance to veto moves to admit the two countries.
White House press secretary Jen Psaki said Washington is "working to clarify Turkey's position" and believes there is "broad support" among NATO members for the two countries to join.
It comes as US secretary of state Antony Blinken is scheduled to meet his NATO counterparts, including the Turkish foreign minister, this weekend in Germany.
The Turkish president earlier explained his opposition by citing Sweden and other Scandinavian countries' alleged support for Kurdish militants and others considered by Turkey to be terrorists.
Watch: Ukraine - Vladimir Putin blames Russian invasion on Western policies.
He said he also did not want to repeat Turkey's past "mistake" when it agreed to readmit Greece into NATO's military wing in 1980.
He claimed the action had allowed Greece "to take an attitude against Turkey" with NATO's backing.
Mr Erdogan did not say outright that he would block any accession attempts by the two Nordic nations, but NATO makes all its decisions by consensus, meaning each of the 30 member countries has a potential veto over who can join.
Russia's aggression in Ukraine prompted Finland and Sweden to reconsider their traditions of military non-alignment.
Public opinion in the two countries quickly started to shift towards favouring NATO membership after Russia invaded Ukraine on February 24.
Should the two countries proceed on that path, it would represent a blow to Russia since President Vladimir Putin cited NATO's expansion near Russian territory as one of his justifications for invading Ukraine.