Washington (CNN) The election-day fundraising blast from the Democratic Congressional Campaign Committee raised hopes that a potentially blockbuster moment for the anti-Donald Trump resistance was coming in a special election for a House seat in Montana.

"We could actually hand Trump a SHOCKING loss tonight," it told potential donors on the DCCC's email list, including 2.3 million people added just this year.

Privately, though, Democratic leaders had long known their internal polling showed Republican Greg Gianforte on track to defeat their candidate, Rob Quist. The party had spent a modest $500,000 on the race -- paltry, compared to the $2 million more the DCCC's chairman had announced just a day earlier it would spend on a race in Georgia.

The refusal to spend heavily in Montana, which follows a similar decision in a special election for a House seat in Kansas, has left some progressives howling that even as an energized base breaks off-year fundraising records, the party's infrastructure isn't trying to win back the red territory where Bernie Sanders won Democratic nominating contests and then Trump trounced Hillary Clinton in the general election last year.

After Gianforte won by 6 percentage points, the DCCC bragged in a memo that when its early investments didn't move the numbers, the party "refused to waste money on hype."

It has in some ways exposed rifts over the party's approach that are still lingering from the Sanders vs. Clinton contest, particularly after Sanders spent the weekend before the Montana contest campaigning alongside Quist.

"You have to ask yourself, could this have been different had we actually invested more resources in that race?" said Lucy Flores, a former Nevada assemblywoman and board member of the Sanders-aligned Our Revolution.

"We are dealing with the most disappointing and concerning government we've seen in my adult life -- and that results in a lot of pressure to win in races that are a stretch," said Tom Lopach, a Democratic operative who led the Democratic Senatorial Campaign Committee in 2016.

Markos Moulitsas, the founder of the liberal blog Daily Kos, said he is hesitant to criticize the DCCC because its job is to win back the House -- and that means tough decisions about where to spend limited resources.

"But I will say this: Part of winning next year will depend on an energized liberal base," Moulitsas said.

If Democrats can continue to narrow major gaps in the size of Trump's win compared to GOP congressional candidates' victories next year, he said, "a heck of a lot of Republicans are in serious trouble."

"And guess what? Showing you won't back down from a tough fight breeds loyalty and support," Moulitsas said. "Our readers and donors knew exactly what they were doing when they donated money for those long-shot races. And they didn't care, because we're putting serious pressure on the GOP, and they won't be able to outspend us 6-to-1 on every race next year."

New Mexico Rep. Ben Ray Luján, the DCCC chairman, argued that Democrats are making "smart investments, specific to those districts."

Meanwhile, the Republican super PAC Congressional Leadership Fund pumped millions of dollars into the Montana race, easily outspending the left.

"Republicans should be worried that they've had to dump so many dollars in to try to defend a district that they shouldn't have had to spend a penny in," Luján told reporters.

Wave coming in 2018?

For the Democratic establishment, part of the struggle is that -- with progressives' eyes on a quartet of House special elections in traditionally Republican districts -- its investments are being closely watched, especially with what's expected to be a much broader than usual battlefield in the 2018 midterm elections.

Many Democrats see in 2018 a potential wave election similar to 2006, when then-President George W. Bush's declining popularity allowed the party to sweep into power in the House.

But in 2006, the Howard Dean-led Democratic National Committee had launched a "50-state strategy." New DNC Chairman Tom Perez has promised a return to that 50-state approach -- but he is in the early stages of rebuilding the DNC from the ground up.

That means the national party isn't well positioned to play a supporting role in the House special elections.

"The easiest decision to make in politics is to spend more money. The hardest decision in politics is where to cut it from," said Jesse Ferguson, a Democratic operative who led the DCCC's independent expenditure arm in the 2014 election cycle.

"It's a gut-wrenching decision to pull money away from a candidate who might win in favor of a candidate who has a better shot at winning. But that's what we have to do in order to end Trump and Paul Ryan's rule of Congress," Ferguson said.

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On the Senate side, Democratic incumbents in states Trump carried -- including Missouri Sen. Claire McCaskill, Montana Sen. Jon Tester and North Dakota Sen. Heidi Heitkamp -- have already made a point locally of broadening their outreach as Trump's White House moves to appease the President's base, Lopach said.

"We as a party have got to get back to economic, pocketbook, kitchen-table issues -- because an economic issue affects you if you are a black voter, brown voter, white voter, if you're a woman voter, LGBTQ voter," Lopach said. "I think we've lost sight of the fact that economic issues are overarching."

The DCCC has invested much more heavily than in Montana in the June 20 runoff in Georgia, where Jon Ossoff will attempt to claim the seat in the northern Atlanta suburbs previously represented by former House Speaker Newt Gingrich and current Health and Human Services Secretary Tom Price, both Republicans.

And the party has identified some rural districts, and others in the industrial Midwest, as top targets for next year.

But Democrats are wise to closely guard their resources with so many potentially competitive Republican seats on the map in 2018, Ferguson said.

"No one wants to be in a position in the fall of telling a promising candidate in a competitive district that the resources aren't there because they were spent 18 months earlier as part of a Pyrrhic victory," Ferguson said. "Pyrrhic victories don't get a vote for House speaker."