These are not happy times for Republicans. Though their party controls Congress and the White House for the first time since the days of George W. Bush, they haven't so far passed any landmark legislation and, after weeks of stumbles and embarrassments, GOP legislators are spending the Easter recess facing irate constituents. While the ruling party languishes in turmoil, progressives have been oddly hopeful for the past couple of weeks. Their pep stems in large part from the fact that everyone's favorite socialist uncle, Senator Bernie Sanders, is back in the limelight, pushing his lefty legislative agenda and commanding a newfound prominence as the most popular Democrat (although he's technically not a Democrat) in America.

Sanders drew attention towards the end of last month when he vowed to introduce a bill proposing a wholly government-run (a.k.a. single-payer) healthcare system after the failure of the GOP's big healthcare plans. At the start of April, he and several allies got great press for a new bill that would make public four-year colleges and universities free for Americans from families making less than $125,000 a year. Other progressives have similarly articulated legislation that'd expand Medicare or paid family leave, and Sanders has been barnstorming for issues like raising the minimum wage and improving union protections.

None of these proposals are new—Sanders hasn't really changed his views over the years. What's changed is that more Democratic lawmakers are now backing his and other progressives' bills. Sanders's proposals obviously won't become reality as long as the GOP controls Congress—but the Vermont senator's sustained push for his legislative agenda will likely have a real effect on national politics moving forward, however slowly that process occurs.

Some progressives imagine a universe in which a chastened and pragmatic Trump works with Sanders toward providing healthcare for all Americans. Trump—or so this vision goes—has endorsed a single-payer system in the past (see his 2000 tome The America We Deserve) and some polls show that most Americans would embrace such a scheme. Trump's said if he can't work with the GOP on healthcare, he'll work with Democrats, and Sanders has offered to reach out to the White House.

That universe seems a long ways away. In reality, Trump is often uninformed and erratic; his policies and actions to date do not indicate a willingness or ability to move towards Sanders's views. The people in the Trump orbit who care about healthcare—from House Speaker Paul Ryan to Health and Human Services Secretary Tom Price—would never endorse a Sanders-esque plan, and a Republican Congress wouldn't pass it. "Even if they did" want to advance a Sanders talking point, said Michael Heaney, a University of Michigan expert on social movements and party politics, "they still wouldn't want to get behind it for partisan reasons."

Sanders has admitted his agenda likely won't fly as is in this climate. But, explained Democratic strategist Jonathan Tasini, "you have to view this [legislative push] and Sanders's role as a long game," aiming to change national political dialogue years down the road.

"The long-term strategy is to build support within the Democratic Party itself, among both elected officials and Democratic primary voters," for progressive policies, expanded Boston College party dynamics expert Dave Hopkins, "so that the party's legislative agenda-in-waiting is further to the ideological left for the next presidential election in 2020."

Though Sanders lost to Hillary Clinton in last year's primaries, he's remained popular—thanks in part to the common belief among progressives that "Bernie would have won." He's moved from the political fringes to a leadership position among Senate Democrats and had success promoting progressive candidates. He's held rallies, launched a podcast and a Facebook Live show, and generally remained in the public eye far more than most unsuccessful presidential candidates. Which is to say, he has real and substantive political clout these days.

This doesn't mean that Sanders and his allies can take over the party, cautioned Heaney. The limits of Sanders's powers were on full display when Minnesota Congressman Keith Ellison, his pick for Democratic National Committee chairman, lost out to the more centrist Tom Perez a few weeks back. (Perez and Sanders are currently on a "unity tour" to show there's no bad blood between the two wings.) Even if Ellison had taken charge, Heaney noted, the Democratic Party tends not to fall into line behind leadership as readily as the GOP, and centrists have a host of pragmatic reasons not to go full socialist.

"The dominant style of governing in the Democratic Party is technocratic incrementalism, not ideological revolution," added Hopkins. "There just isn't a broad enough constituency within the party, to say nothing of the American electorate, for Sanders's kind of politics to become the favored approach of the national party any time soon."

But Sanders can—and likely will—drag the Democratic agenda leftward. The party is reportedly developing a new platform that is more progressive and populist on issues like trade, and Heaney suspects that individual Democrats will pick up at least some of it in future races.

For his part, Sanders seems fully aware of and content with the fact that he's helping with a slow leftward shift. Heaney suggested he's trying to float as many ideas as he can, airing them out in vital swing states to give Democrats a sense of what issues might gain traction and how to package them in the future. So far, however, it's too soon to say what will stick, especially since the most powerful (and probably effective) issue uniting Democrats at the moment is hatred of Trump.

But sooner or later Democrats will have to put forth a statement of what they're for, not what they're against, which is why Sanders still matters. "All of this is incredibly important," concluded Heaney, "because it's laying the groundwork for an insurgent candidate to come along and take on Donald Trump."