From Longman Dictionary of Contemporary Englishparty lineˈparty line noun [singular] PPPthe official opinion of a political party or other organization, which its members are expected to agree with and supportfollow/toe the party line (=to support the official opinion) He refused to toe the party line.
Examples from the Corpus
party line• I am almost embarrassed because our answers appear to be a party line.• But the House, in a party line vote, Tuesday refused to grant the extension.• As Communists they followed the party line only loosely.follow/toe the party line• However, both sides developed a centralized party organization, with politicians following the party line.• As Communists they followed the party line only loosely. 