Just as the sun started to break through on Saturday afternoon, members of the homeless advocacy group Respect Line began planting their colorful signs and banners on the New Haven Green.

The group, which stood at the corner of College and Chapel streets, was preparing for a trial run of “Street Theater” — an outdoor assemblage of artistic displays and performances by local residents, homeless people, and students. Street Theater will officially begin on Wednesday, and continue every afternoon on the Green, Sundays excluded, until the end of the month.

The event is part of a larger community-wide effort to raise enough money to keep the Overflow Men’s Shelter on Cedar Street open this summer. The city-funded shelter, which has been in New Haven for more than a decade, is scheduled to close as usual on April 30.

This year, though, local community members are calling for a change. Several weeks ago, an ad hoc group decided to resist the planned closure of the shelter.

“When it became apparent to us three or four weeks ago that we were going to go over a cliff, a bunch of us started talking about it,” said Ward 10 Alderman Ed Mattison LAW ’68, who helped to organize the newly formed Overflow Crisis Advisory Committee.

OCAC members include several people from Respect Line, figures from the religious community, and students from Yale Hunger and Homelessness Action Project. Interfaith Cooperative Ministries, Inc. recently agreed to be the fiduciary agent for OCAC, and the small group now faces the task of raising tens of thousands of dollars by April 30.

Respect Line organized Street Theater to show its support for OCAC, and to help raise awareness of the issue. The Rev. Ron Rising of First and Summerfield United Methodist Church, a member of OCAC’s advisory board, said a benefit concert will be held at his church on April 27.

The cost of operating a basic shelter for the next six months would be approximately $80,000, and Mattison said New Haven Mayor John DeStefano Jr. has vowed to match up to $40,000 of the money OCAC can raise in the next few weeks. Mattison said the mayor did not specify where his funds would come from.

The mayor’s office declined to comment Friday.

Mattison emphasized that OCAC is not asking for money from the city, but is seeking financial support and volunteers from the community at large.

“New Haven spends more local tax money on homeless people than all other municipalities in Connecticut put together,” Mattison said.

He said the city spends $1.4 million on homelessness each year. Despite recent economic setbacks and budget cuts, Mattison said the city has still allotted the same amount for homeless services in the upcoming year’s budget, and that OCAC could not ask the city to keep the overflow shelter open.