A group that supports the Mashpee Wampanoag’s proposal to build a casino in Taunton has spent more than $130,000 on a political campaign to win favor for the project, outspending opponents more than 175 to 1 ahead of Saturday’s nonbinding referendum, according to documents on file with the city clerk.

The Mashpee tribe has committed $300,000 toward the public campaign that is being waged on behalf of the tribe by the group Together for ­Taunton, which includes local residents, business owners, and tribal members. The group had about $170,000 in cash on hand on May 22, the most ­recent date covered by the group’s filing. The group expects to spend all the money on the campaign before Saturday’s vote. Opponents, on the other hand, had spent just $730 to ­defeat the proposal by May 31. The opposition group, Preserve Taunton’s Future, had $793 on hand at the end of last month.