The claim is true because multiple reliable sources confirm that Oklahoma passed a bill banning child marriage, and 36 Republican lawmakers voted against it.
Democrats pass bill ending child marriage in Oklahoma. 36 Republicans voted no.

Were all 36 votes against a recently passed bill that bans child marriage cast by Republican lawmakers? - Oklahoma Watch
Source: oklahomawatch.org
Key Evidence
Senate Bill 504 bans child marriage in Oklahoma with a minimum age of 18 and no exceptions.
The Oklahoma Senate passed the bill unanimously; however, in the House, 36 Republicans voted against it.
Governor Stitt allowed the bill to become law without signing it.
Opposition from Republicans was largely based on objections to the bill's strictness and ideological reasons.
What the Evidence Shows
The bill in question, Senate Bill 504, was passed into law in Oklahoma with the intent to end child marriage by setting the minimum marriage age at 18 with no exceptions. The bill passed unanimously in the Oklahoma Senate but faced opposition in the House, where exactly 36 Republican representatives voted against it. These votes were primarily due to objections over the lack of exceptions in the bill and concerns about government interference in parental rights.
Governor Kevin Stitt neither signed nor vetoed the bill, allowing it to become law without his signature. Multiple sources, including local news outlets, advocacy groups, and political commentary, consistently report that all 36 no votes came from Republicans. Some Republicans cited religious or family values as reasons for their opposition.
The bill is set to take effect on November 1, 2026.