Colorado and Nevada have joined California, Oregon and Washington in the Western States Pact, an alliance of state leaders working together to reopen their economies while mitigating the spread of the coronavirus.

Govs. Jared Polis of Colorado (D) and Steve Sisolak of Nevada (D) announced their states’ participation on Monday.

The pact, which first formed two weeks ago, involves sharing information and agreeing to meet a set of benchmarks before relaxing social distancing orders. The five states agree that any lifting of shelter-in-place rules will come with the development of a system for testing, tracking and isolating those with coronavirus symptoms. The pact also calls for increased hospital capacity and protective gear, as well as a plan for protecting vulnerable populations, especially those in nursing homes.

“There’s no silver bullet that will solve this pandemic until there is a cure,” Polis said in a statement Monday, “so we must have a multifaceted and bold approach in order to slow the spread of the virus, to keep our people safe and help our economy rebound.”

“Millions of visitors from our fellow Western states travel to Nevada every year as a premier tourism destination, and this partnership will be vital to our immediate recovery and long-term economic comeback,” Sisolak said.

With their participation, the pact now encompasses about one-fifth of the U.S. population.

AAron Ontiveroz/MediaNews Group/The Denver Post via Getty Images via Getty Images Colorado Gov. Jared Polis (D) called the commitments in the pact a "multifaceted and bold approach."

The West Coast states first formed the pact as President Donald Trump began pushing to reopen the economy despite public health experts warning that returning to business as usual wouldn’t be possible without widespread COVID-19 testing, increased hospital capacity, a drop in outbreaks or other factors.

The same day the pact formed, Trump suggested he could force states to restart their economies, falsely asserting that the president’s “authority is total.”

“It’s total,” he said. “And the governors know that.” Outside the pact, a handful of states have proceeded to reopen their economies. The state to most aggressively do so is Georgia, whose governor recently allowed hair and nail salons, gyms, bowling alleys, tattoo studios, massage therapists, theaters and restaurants to reopen.

California Gov. Gavin Newsom (D) thanked Colorado and Nevada for getting on board with the pact, noting the importance of nearby states agreeing to the same guidelines.

“I want to thank Colorado and Nevada for joining the Western States Pact,” he said. “COVID-19 doesn’t follow state or national boundaries, and it will take every level of government, working together to get the upper hand on this virus.”

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