Progressives could learn a thing or two from conservative activists who put targets on the backs of GOP lawmakers.

So many of today's top Republican lawmakers — like Sens. Mike Lee (Utah), Rand Paul (Kentucky), and Marco Rubio (Fla.) — were relative outsiders who won election in 2010 after toppling better-known and better-funded establishment Republicans (three-term Utah Sen. Bob Bennett, Kentucky Secretary of State Trey Grayson, and Florida Gov. Charlie Crist, respectively). Even when this strategy failed (think Sharron Angle in Nevada and Christine O'Donnell in Delaware), it was a critical early Obama era effort on behalf of conservative donors and activists. They sought not only to displace Democrats from office, but also many moderate and establishment Republicans, too. And in the years since, some of the most conservative Republicans in the House and Senate have repeatedly faced either well-funded or well-supported primary challengers who are even more right-wing than they are. This is an important reason why the national GOP has skidded so far to the right in recent years.

On the other side, however, moderate Democrats have rarely faced the same challenges from their left flank. In more conservative states, the excuse is usually that moderates like Mark Pryor (Arkansas) or Mary Landrieu (Louisiana) are the best the Democrats could possibly do, given the circumstances. In liberal states, like New Jersey — which has one senator who opposed the Iran deal and another who sat on the board of directors for the Alliance for School Choice with Betsy DeVos — the excuse is often a lawmaker's close proximity to an industry that requires "pro-business" policies.

Enough is enough.

If Democrats want to regain national power, they must stop cynically and brazenly triangulating. They can no longer just quietly lament their centrist leaders. Progressives must fight back. They have to take on moderate, establishment-backed Democrats in primaries — even, in some cases, incumbents — who don't embody the core ideals of a progressive movement positioning itself to be a real alternative to the GOP.

The Democratic Party has long been averse to intra-party conflict. But you needn't look farther than the 2016 presidential race to see how hungry so many Democratic voters are for progressive alternatives.

Well before the primary officially kicked off, Hillary Clinton all but cleared the field, with only former Maryland Gov. Martin O'Malley given any sort of a chance. What happened instead is that Vermont Sen. Bernie Sanders, a democratic socialist who has railed against the two-party system for his entire career, took a longshot bid all the way to the last primary, garnering around 43 percent of all votes cast, winning 23 contests, and putting up a surprisingly strong fight in pretty much every region of the country apart from the South.

With President Trump and the Republicans now in unified control over the federal government, it's all the more important to provide real choices in what the opposition to Trump should look like. In open primaries for who gets to face Republicans, leftist activists should be organizing right now to decide who the progressive candidate will be, as establishment Democrats looking to take on Republicans in winnable seats are assuredly already making calls and lining up endorsements.

If Trump's first days in office are any indication, his presidency promises to be a historic disaster for the working class, which means that if Democrats mobilize, they'll have a tremendous opportunity in 2018. Pretty much any House, Senate, or governor's seat they could possibly dream of having a chance at may well be fair game. But incredibly, some Democrats don't see it that way; as Rachel Cohen wrote for the American Prospect, Democrats in Maryland are shying away from taking on Larry Hogan, the Republican governor of a very Democratic state who's up for re-election in 2018. Why? "He's moderate and just too well-liked," Cohen was told.

It's long past time for Democrats to shed this sense of defeatism toward races against Hogan and others, like Massachusetts Gov. Charlie Baker (R), just because the GOP incumbent is popular now. A lot can change in two years, especially when the face of the Republican Party is someone as volatile as President Trump.

But while Republican-controlled seats should unquestionably be the focus, it's also true that no Democrat — no senator, no member of Congress, no governor, and no state legislator — should be able to take their own renomination in 2018 for granted if they cosign any part of the right's agenda to privatize everything, install the extremely wealthy in the halls of government, and roll back decades worth of social progress.

A good first litmus test for this? Votes on the confirmation of Trump's Cabinet nominees. Progressives should be prepared to fight, with full force, everyone who is willing to hand over the federal government to people like DeVos, Labor nominee Andy Pudzer, Treasury nominee Steven Mnuchin, and attorney general pick Jeff Sessions.

There is a real need for fresh blood in the Democratic Party; not just in districts that could be flipped from Republican hands, but in safe seats occupied by Democrats who came to prominence through aligning themselves with the Third Way. After all, this is the faction of the party that ultimately negotiated the public option out of the Affordable Care Act, which arguably contributed to the law's pending doom.

Trump is president. And so the clock is already ticking for 2018. Progressives have to start organizing now for better options at the ballot box, and ultimately, a better future.