Senate Democrats are set to announce a new push for single-payer healthcare on Wednesday featuring several 2020 hopefuls touting legislation from Sen. Bernie Sanders, I-Vt., to expand Medicare to everyone.

But divisions remain in the Democratic caucus over whether government-run healthcare may be going too far. Some of the most vulnerable Senate Democrats running for re-election in 2018 are not offering a warm embrace of the policy.

Instead, some Democratic senators are angling to expand Medicare to people ages 55 and up, from the current 65 years old.

Neither expansion of Medicare is expected to go anywhere in the Republican-controlled Senate. The rift, however, does illustrate divisions in the Democratic Party on what their next step will be after Obamacare.

Single payer has been an idea traditionally pushed on the left fringes of the Democratic Party. However, it is a policy idea that has gained greater mainstream appeal after Sanders' surprise run last year for the party's presidential nomination.

Democratic Sens. Cory Booker of New Jersey, Kamala Harris of California, Elizabeth Warren of Massachusetts and Kirsten Gillibrand of New York, all of whom have been suggested as 2020 presidential hopefuls, are among the co-sponsors of Sanders' bill.

Booker was asked by reporters whether signing on to the bill is a sign for people who are thinking about running for president in 2020.

"I hear that for every decision that is being made," he said.

Populist Democratic Sen. Sherrod Brown of Ohio touted legislation to expand Medicare for people ages 55 and up when asked about whether he supports the Vermont independent's bill.

"Between 55 and 64 is a time when a lot of people lose insurance and it gives people the option of joining," he said. "It is the most important step we should take now."

Reporters asked Brown if expanding Medicare to 55 was more achievable than single payer.

"It's what I am working on," Brown responded.

Other Democrats were reticent to support single payer, especially those up for re-election in 2018 in states that President Trump won handily.

"I've been very focused on making sure the Affordable Care Act works for the people of my state," said Sen. Heidi Heitkamp, D-N.D., who is running for re-election in a state Trump carried by 36 percentage points. "That is where my focus is going to be."

Sen. Joe Manchin, D-W.Va., who is up for re-election in a state Trump won by 42 percentage points, told Bloomberg that single payer should be explored.

However, Manchin's office sent a statement quickly walking back those remarks.

"I am skeptical that single-payer is the right solution, but I believe that the Senate should carefully consider all of the options," Manchin said in the statement.

In the House, top Democrats are not on board.

House Minority Whip Steny Hoyer of Maryland said Tuesday that Medicare-for-all would have "significant administrative and other issues." He said the House Democratic leadership is focused more on preserving Obamacare.

House Minority Leader Nancy Pelosi also said that the most immediate goal is protecting Obamacare, declining to endorse the bill.