Amendment 69, the ballot measure known as ColoradoCare that would have created a universal health care system in Colorado, was soundly defeated Tuesday night.

At 8:30 p.m., with nearly 1.8 million votes counted across the state, the amendment was trailing 79.6 percent to 20.4 percent, according to preliminary state figures. Updated vote totals at 7 a.m., with 86 percent of the vote counted, the measure continued trailing at roughly the same percentage or 1,833,879 to 467,424. Throughout the campaign, the measure had polled better with Democrats than Republicans. But even in left-leaning Denver, the amendment was losing 2-to-1, according to early returns.

At a downtown Denver watch party for supporters of the measure, the mood was quiet but not yet resigned to defeat.

“The early returns, I hope, are not reflective of Colorado,” said state Sen. Irene Aguilar, a Denver Democrat who is one of the amendment’s leading backers.

But supporters also acknowledged it was unlikely the measure would recover and vowed they would try again another year.

“We learned a lot,” said T.R. Reid, an author who is another of the amendment’s most prominent supporters. “And we’ll definitely be better next time.”

Opponents declared victory.

“We’re grateful to the people of Colorado for carefully considering Amendment 69 and voting overwhelmingly against a measure that was clearly risky, untested, and fiscally irresponsible,” Kelly Brough, president and CEO of the Denver Metro Chamber of Commerce and chair of opposition group Coloradans for Coloradans, said in a statement.

Amendment 69 would have eliminated most private health insurance in the state and replace it with a taxpayer-funded cooperative known as ColoradoCare, which would have provided coverage to every single Colorado resident. It would have been paid for, largely, through a 10 percent payroll tax — workers at businesses would have been responsible for a third of the tax, while their employers would have picked up the rest; the self-employed would have paid the full 10 percent. The cooperative’s budget, at about $36 billion a year when fully implemented, would have dwarfed the state government’s budget.