After back-to-back presidential losses, Republicans in key U.S. states want to change the rules to make it easier for them to win.

From Wisconsin to Pennsylvania, Republican officials who control legislatures in states that supported President Barack Obama are considering changing state laws that give the winner of a state's popular vote all of its Electoral College votes, too. Instead, these officials want Electoral College votes to be divided proportionally, a move that could transform the way the country elects its president.

In the U.S., the president is not elected by popular vote but rather on a state-by-state basis where, in most cases, the candidate that wins the state gets all of the electoral votes that are then tallied to determine a winner.

Republican National Committee Chairman Reince Priebus endorsed the idea this week, and other Republican leaders support it, too, suggesting that the effort may be gaining momentum. There are other signs that Republican state legislators, governors and veteran political strategists are seriously considering making the shift as the party looks to rebound from presidential candidate Mitt Romney's Electoral College shellacking and the demographic changes that threaten the party's long-term political prospects.

"It's something that a lot of states that have been consistently blue that are fully controlled red ought to be looking at," Priebus told the Milwaukee Journal Sentinel, emphasizing that each state must decide for itself. States that vote Democratic are considered "blue," while states that vote Republican are considered "red."

Democrats are outraged at the potential change.

Obama won the popular vote with 65.9 million votes, or 51.1 per cent, to Romney's 60.9 million and won the Electoral College by a wide margin, 332-206 electoral votes. It's unclear whether he would have been re-elected under the new system, depending upon how many states adopted the change.

While some Republican officials warn of a political backlash, party lawmakers in Michigan, Wisconsin and Pennsylvania are already lining up behind proposals that would allocate electoral votes by congressional district or something similar.

Michigan Gov. Rick Snyder told The Associated Press on Tuesday that he "could go either way" on the change and doesn't plan to push it. But he said it's a reasonable issue to debate and that he prefers that leaders discuss it well before the next presidential election.

"It could be done in a thoughtful (way) over the next couple years and people can have a thoughtful discussion," Snyder said.

Democrats aren't convinced. And they warned of political consequences for Republicans who back the shift — particularly those governors up for re-election in 2014, which include the governors of Michigan, Wisconsin and Pennsylvania, among others.

"This is nothing more than election-rigging," said Michigan Democratic Chairman Mark Brewer.