The governors of California, New York, Illinois and Connecticut, among others, have ordered their residents to stay home in order to slow the spread of the coronavirus. Massachusetts Gov. Charlie Baker has, so far, resisted that step. But he's facing growing pressure to do so.

More than 50 elected officials, including state lawmakers and municipal office-holders from around Greater Boston have signed a letter urging Baker to impose a shelter-in-place order immediately. They include state Rep. Mike Connolly, of Somerville, who believes Massachusetts should follow the example of other states where millions of residents are under orders to stay home.

"We can actually control how this coronavirus spreads, and the control, of course, comes by getting as many people as possible to stay home," he said.

Connolly believes Massachusetts is doing a lot to combat the spread of the virus, but he argues that Baker needs to do more to keep people home.

"We’re hearing way too many examples of people who aren’t taking this seriously, or people who want to take this seriously but are being pressured to go into work," he said. "That’s why we’ve been calling on Gov. Baker to issue a shelter-in-place or a stay-at-home order.”

Connolly said the order should allow people out to buy food and medicine, to care for someone in need, to do an essential job or even to take a walk. Otherwise, they should stay home.

Baker has shut down the state’s schools, limited restaurants to takeout and delivery only and banned gatherings of more than 25 people. But he says there are no plans for a statewide shelter-in-place order. He argues that many activities and much of the state’s economy are already shut down.

"People have expressed the fact that their once thriving downtown is now a ghost town," Baker said Friday. "We are very much in social distancing and shutdown mode here in Massachusetts based on what we’ve already done.”

Baker says his administration is following the advice of public health experts. But many members of the medical community believe the state should impose a stay-at-home order now.

“I think we should — to decrease the transmission and not overwhelm the healthcare system," said Dr. Thomas Tsai, a surgeon and health policy researcher at Brigham and Women’s Hospital.

Tsai told WBUR last week that the big challenge is that Massachusetts — and the nation as a whole-- are behind in testing for coronavirus, which means we still don’t fully understand who is infected — and where they are.

“The only tool we have left is to stay at home," he said. "Even though the guidance may allow getting a haircut or going to the nail salon, I think that’s socially irresponsible at this time.”

On Sunday, Greater Boston Physicians for Social Responsibility called on Baker to issue a stay-at-home order.

Meanwhile, in the absence of statewide guidance on the issue, cities and towns are left to consider their own policies. Joe Curtatone, mayor of Somerville, applauds some of what Baker has done, but said he would like to see uniformity across the state to limit the spread of the virus.

“We know this virus doubles every three to five days," he said. "Where Italy was on March 11, we are today. And the only way to prevent transmission [is] extreme social distancing."

On Sunday, the Nantucket Select Board approved a stay-at-home order, believed to be the first community in Massachusetts to do so, after a resident tested positive for COVID-19. There are no such plans in Boston, but Mayor Marty Walsh says that could change.