Voters cast ballots at Denver's 14th Avenue and Bannock Street polling station on Tuesday, Nov. 6, 2018. (Jesse Paul, The Colorado Sun)

Colorado’s governor has signed into law a bill to have the state join others in bypassing the Electoral College system and casting their presidential electoral votes for the winner of the national popular vote.

Gov. Jared Polis signed Senate Bill 42 on Friday afternoon. He’d long said he supported the measure.

MORE: Colorado lawmakers are sparring over a plan to bypass the Electoral College. Here’s what’s at stake.

The legislation was made law without a public ceremony and at least one of the measure’s prime sponsors, sate Sen. Mike Foote, a Lafayette Democrat, was not present. The governor typically signs major pieces of legislation with its sponsors, posing for photos.

Colorado joins 11 other states and the District of Columbia in what’s called the National Popular Vote Interstate Compact.

The pact would take effect after states with a collective 270 electoral votes — the number needed to win the presidency — agree to join.

With Colorado’s nine electoral votes, compact members have 181. The state legislatures in Delaware and New Mexico are also weighing whether to join.

Opponents say the initiative subverts an Electoral College that ensures that smaller states aren’t trampled when it comes to choosing a president. Republicans in the Colorado legislature mounted a fierce effort in opposition to the bill.

Not a single GOP vote was cast in favor of the measure as it cleared the Capitol.

Monument Mayor Don Wilson and Mesa County Commissioner Rose Pugliese, both Republicans, have vowed to try and overturn the national popular vote measure by putting the question before voters. They would need to collect 124,632 signatures to put the question on the ballot.

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Five of the nation’s 45 presidents have won the Electoral College vote and not the popular vote, including Republicans Donald Trump in 2016 and George W. Bush in 2000.

Colorado Sun staff writer Jesse Paul contributed to this report.

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