Bernie Sanders and democratic socialism increasingly look to be winning over the Democratic Party, raising concerns among some Democrats about whether it could hurt the party in this year's midterm elections, and the presidential race of 2020.

The biggest Democratic star of the summer is Alexandria Ocasio-Cortez, who, like Sanders, is a democratic socialist.

Prospective Democratic candidates in the 2020 presidential election are flocking to the Sanders "Medicare for all" bill, which would institute a single-payer health-care system across the country.

And a new Gallup poll this week found that 57 percent of Democrats view socialism favorably, compared to 47 percent who view capitalism positively.

Two years after Sanders energized progressives during the 2016 Democratic presidential primary, it all suggests the Democratic field in the upcoming primary will be pulled more and more to the left as candidates compete for a large slice of their party's electorate.

"Bernie Sanders lost the war but won the battle to reshape the party," said Brad Bannon, a Democratic strategist.

What that means in the general election against President Trump is another question.

A number of Democrats are worried their party could be hurt by an association with leftist politics, which they fear could cost them Trump voters and independents.

Republicans, for their part, practically salivate over the chance to tie Democrats to socialism - beginning with this fall's midterms.

"It would be a disaster for them. They would guarantee a Trump victory," said Shermichael Singleton, a Republican strategist who has been opposed to many of the president's policies. "I would square it to committing political suicide."

"It's the kiss of death nationwide in a general," added Republican strategist Susan Del Percio, who has also frequently disagreed with Trump's policies.

Sanders, for his part, doesn't sound too worried.

In an interview Wednesday night on CBS's "Late Show," Sanders said democratic socialist ideas are "mainstream" after host Stephen Colbert pressed him over whether an association with socialism would taint Democratic candidates.

"I think the real issue is that the ideas that we've been talking about, almost without exception, are now ideas that are mainstream ideas and are supported by the vast majority of the American people," Sanders said.

Democratic strategist Basil Smikle - who served as the executive director of the Democratic Party of New York and worked for Hillary Clinton - said the Gallup polls suggest Sanders's policies continue to be attractive to the younger voters both parties are seeking to claim.

Fifty-one percent of those 18 to 29 years old have a positive view of socialism, according to the Gallup poll.

"The poll suggests that if Democrats are to grow the party with younger, more diverse voters, we need to pay attention to their political impetus for supporting these policies," Smikle said. "Younger voters, who seem the most attracted to socialism, are keenly aware of global inequality and see the U.S. as lagging in its political will to build more fairness in our economy."

Bannon, the Democratic strategist, said the prevailing wind in Democratic politics is good news for Sanders and Sen. Elizabeth Warren (D-Mass.), as it clearly gives them a shot at the presidential nomination.

"Democrats who don't support Medicare for all and other Sanders proposals will swim against the tide during primary and caucus season," he said.

At the same time, he conceded that "what works in the spring doesn't always translate to votes in the fall."

Republicans such as Del Percio think Republicans could make an effective argument in using socialism against Democrats.

"If people were wondering how Trump won in the Rust Belt and they'd like to see him do it again, then yes, put in a Democrat who calls himself a socialist," she said. "It would be very difficult for Democrats to pick up a significant amount of support should they embrace a socialist message."

That's certainly been conventional wisdom for decades.

But the Gallup poll, and Sanders's popularity, has more than one Democrat questioning whether the tides are changing - particularly as Americans voice frustration about income inequality and a growing economy that still leaves many poor and middle-class voters struggling to send their kids to college.

Democratic strategist Celinda Lake said socialism "has become code for progressive economics" and that many Democrats would fall into that category even if they didn't call themselves "socialists."

Even a candidate such as former Vice President Joe Biden, who is likely to position himself to the right of Sanders and Warren in a primary, will back progressive policies on the economy and health care, Lake said.

Sanders really began shaping the Democratic Party during his primary bid against Clinton in 2016.

Many of his policies made it into the Democratic platform, reflecting his growing power and the desire among Democrats to bring his supporters into the fold.

"We have made enormous strides," Sanders said in a statement in July of 2016. "Thanks to the millions of people across the country who got involved in the political process - many for the first time - we now have the most progressive platform in the history of the Democratic Party."

In the end, that effort was not completely successful, however, given Clinton's loss to Trump.

Sanders also angered Clinton supporters in 2016 by running in the Democratic primary even though he isn't a Democrat.

The Democratic National Committee is considering a rule change next week that would require candidates running for the party's presidential nomination to run as Democrats.

The Sanders force is also seen in the fact that other Democrats are backing his single-payer push, including Sens. Kamala Harris (Calif.), Cory Booker (N.J.) and Kirsten Gillibrand (N.Y.), who are all seen as potential presidential candidates.

"Bernie's positions used to be fringe ideas. Single-payer was a dirty word in politics," said Chuck Rojas, a Democratic strategist who served as a consultant to Sanders's presidential campaign and was recently one of several advisers who gathered to consult Sanders about the possibility of running in 2020. "Now it's all becoming mainstream. It's a new day."