laboring oar
noun1
An oar that is worked with great effort.
2
US, Broadly, Figuratively The part of a task that requires the greatest effort to achieve.
- And so too, when new issues demanding new policy calls come up within that scheme, Congress presumably wants the same agency, rather than any court, to take the laboring oar.2019, Kisor v. Wilkie (U.S. Supreme Court No. 18-15), Justice Kagan