After Mr. Walker moved to support Iowa’s prized ethanol subsidies, abandoned his support for an immigration overhaul and spoke out against the Common Core national education standards, his pointed tone on marriage caused some Republicans to ask publicly whether he is too willing to modify his views to aid his ambitions.
“It seems like pollsters gone wild,” said Scott Reed, a longtime Republican strategist and top adviser to the U.S. Chamber of Commerce, discussing Mr. Walker’s call for a constitutional amendment.
To Republicans like Mr. Reed, Mr. Walker appears increasingly willing to lose the general election to win the primary.
Mr. Walker’s shifts on issues this year have created friction with a variety of people open to supporting him. He used to oppose what he called government mandates on the use of ethanol in gasoline, for example, but told Iowans this year that he was willing to continue one, the Renewable Fuel Standard. The reversal was not well received in the political network led by the industrialists David H. and Charles G. Koch, according to a Republican aware of the reaction who spoke on the condition of anonymity because of sensitivities over the group’s deliberations.
But his stance on marriage is what has disquieted people who had counted on Mr. Walker taking a more restrained approach to the culture wars.
For several months, according to four people briefed on the discussions who were not authorized to describe an off-the-record meeting, Republican donors who were advocates for legalizing same-sex marriage had worked quietly to try to build bridges to Mr. Walker, whose wife has a lesbian cousin whose wedding reception Mr. Walker attended.