Four years after an Iowa Supreme Court ruling legalized gay marriage in Iowa, a majority of Iowans oppose a constitutional amendment which would overturn it.

According to a Quinnipiac University poll of 1,256 voters conducted July 12-15 and released Monday, 55 percent of Iowa voters oppose an amendment defining marriage as a heterosexual union, while 36 percent are in favor.

Social conservatives angry over the 2009 decision have demanded that lawmakers approve such an amendment and send it to the ballot box. Democrats who control the Senate have resisted.

A majority of Democrats (72%) and independents (58%) oppose such an amendment, but a majority of Republican favor it (58%). Majorities of evangelical Christians (61%) and protestants who attend church weekly (56%) also are in support.

Thirty-one percent of Iowans believe such an amendment would pass constitutional muster.

Only 47 percent of respondents in Monday's poll said that they approve of the marriage ruling, and 44 said they were opposed.

In 2010, opponents organized to oust three justices from the bench. But a 2012 attempt to remove a fourth justice faltered.