Bipartisan appeals have not gone far in Colorado. Not a single Republican voted for the bill as it moved through the state legislature. During a debate on the House floor, one Republican even suggested renaming the bill the “We Really, Really, Really, Really, Really Hate Donald Trump Act of 2019.”

Republican state Sen. Jerry Sonnenberg, who represents the plains east of Denver, worries about the impact of a popular vote on rural America. He said it would lead candidates to only campaign in the largest media markets, like New York and Los Angeles.

“You drop us from nine [electoral] votes to 5.5 million people, all of sudden Colorado is irrelevant,” he said. “This is all about making sure presidential candidates realize Colorado is important to the rest of the country.”

That partisan divide isn’t limited to Colorado. Across the country, pollsters have seen a steep drop in Republican support for a popular vote for president since 2016. National Popular Vote’s Koza said it has been much harder to get Republicans to support his plan in recent years.