WASHINGTON — Colorado Republicans have three months to solve a tricky math problem — or Donald Trump risks losing the state to Hillary Clinton.

The issue is a four-point drop in the party’s share of active voters — a term used by Colorado’s secretary of state to describe residents who will receive mail ballots and, historically, are more likely to vote.

In August 2012, Republicans comprised 36.5 percent of active voters — an advantage of about 5 percentage points over the Democratic “market share” of roughly 31.6 percent.

Despite the GOP edge, President Barack Obama still won Colorado in 2012. And this year, the numbers look more challenging for Colorado Republicans.

Voter registration statistics released Aug. 1 show the GOP has lost significant ground since 2012 as Democrats have held steady and the number of unaffiliated voters has risen.

Of the state’s roughly 3 million active voters, about 32.3 percent are Republican — a drop of about 4 percentage points from four years ago. Democrats, meanwhile, showed a tiny uptick from 31.6 percent to 31.9 percent, pulling nearly even with the GOP.

And independents now comprise Colorado’s largest voting bloc after a rise of 3 percentage points to about 34 percent of active voters — adding a new wild card to the 2016 election.

“The Republican campaign strength is eroding,” said David Flaherty, a Colorado pollster and political consultant who once worked at the Republican National Committee. “It’s going to be very difficult to be successful in November for Republican candidates as long as that continues.”

To be sure, shifts in voter registration do not always forecast results at the ballot box, and the unpopularity of Clinton and Trump has added a new level of uncertainty to the campaign.

Both candidates lost Colorado during the primary, and it’s an open question as to which candidate is doing a better job of bringing supporters of Bernie Sanders or Ted Cruz into the fold.

Plus, despite the four-point drop, active Republican voters still outnumber Democrats by about 11,700 residents: 964,738 to 953,042, according to the secretary of state.

“It’s definitely something we’re paying attention to,” Colorado Republican Party spokesman Kyle Kohli said of the shift in party registration. “But we know it’s not necessarily indicative of how the results will play out this November because of Donald Trump’s appeal to unaffiliated voters, which we see at rallies and events.”

The party made a point of signing up voters during Trump’s visit to Colorado Springs on July 29, he said, and the effort yielded a mix of Republican and unaffiliated supporters.

“He’s speaking to a different crowd,” Kohli said. “We know there are Trump people in the unaffiliated column and we are going to go get them.”

One exit poll from the 2012 election suggests Colorado Republicans have a reason to be optimistic about this bloc of voters. It found independents backed Mitt Romney over Obama 49 percent to 45 percent

And now there are more of them — 1,020,697 to be exact, according to the state list of active voters.

So who are they? Although Colorado independents come in many stripes, political operatives said youth is a common feature; not surprising given the steady migration of young people to Colorado.

“When you consider independent voters in Colorado you have to keep in mind, they tend to be relatively younger voters — and by that I don’t mean a bearded, craft-beer swilling millennial — although many of those people are independents too,” said Lori Weigel, a partner at Public Opinion Strategies, a Republican polling firm.

“But moms of children at home are more likely to be registered independent than to identify with one of the two parties. In fact, moms were one of the most likely subgroups to identify as independent in a late July survey we conducted. And that means the subgroup that tends to decide every statewide election in Colorado — suburban women — will still be critically important this year,” she said.

With three months before Election Day, however, there are signs Colorado could be a tough climb for the GOP. An average of recent Colorado polls showed Clinton ahead of Trump by 8 percentage points; one of those polls, by Fox News, showed she had a 36 percent to 28 percent advantage among Colorado independents. Clinton also outpaced Trump with female voters by 23 percentage points in that same poll.

Notably, too, a super PAC that supports Clinton isn’t investing as much as it could in the state. Priorities USA plans to buy $13.5 million in TV advertising in nine swing states this month. In seven of those states, it’s already on-air, but in two states — Colorado and Virginia — the ads won’t run before Aug. 15.

“Public and private polling, plus our own survey of key Democrats, Republicans, and independent journalists suggests that the GOP is not very competitive in Colorado this year,” wrote veteran political pundit Larry Sabato in a Thursday column explaining why he was shifting his rating of the presidential race in Colorado from “Leans Democratic” to “Likely Democratic.”

The outlook hasn’t stopped either candidate from visiting the state. Nor should these developments suggest that Colorado suddenly has become a Democratic stronghold, said political consultant Curtis Hubbard.

But the changing demographics of the state — including its large Latino population — should worry the GOP long-term, he said. Polls have shown that Trump lags Clinton significantly with this group and the GOP nominee’s rhetoric toward Latinos has raised questions about whether it could harm future Republican outreach efforts.

“Anyone who tries to declare that Colorado is no longer a purple state is usually proven wrong in short order, but it’s easy to see how a party that has trouble appealing to the youth and minority vote will lose stature,” said Hubbard, a former journalist with The Denver Post now serving as campaign manager for Let Colorado Vote, a ballot initiative effort that seeks to give unaffiliated voters more of a voice in Colorado primaries.

He said Colorado unaffiliated voters tend to reflect the rest of the state: evenly divided and often in sync with election patterns that tend to see more liberal or Democratic participation in presidential years.

“But the tide is definitely changing and both parties — but Republicans in particular — are seeing fewer people affiliate as a result of the rise of independent voters,” he said.

The changes come as Colorado absorbs a large influx of new residents — more than 100,000 last year. It is unclear how this is changing Colorado’s demographics and whether it is helping reshape the state’s electorate.

One Colorado Republican operative pointed to a disparity in registration efforts as a reason for the drop in GOP market share. In the past six months, Colorado Democrats have gained a net 48,000 active voters; twice the nearly 24,000 active voters gained by the GOP.

“Democrats have a whole satellite of allies who do voter registration all year round. Republicans lack that,” said Tyler Sandberg, who in 2014 served as campaign manager for U.S. Rep. Mike Coffman, R-Aurora. “They are light-years beyond us.”

While these efforts don’t always yield Democratic voters, he said, the unaffiliated voters who register through these groups tend to lean liberal given that they occur at events such as environmental rallies or gay-rights marches, Sandberg said.

Even so, he warned Democrats should not take these voters for granted and noted that Colorado independents have a stubborn libertarian streak – whether the issue is marijuana or gun control.

“We’re dealing with a small-government crowd,” he said. “We love guns, God, gays and ganja.”

There’s an opportunity there for Colorado Republicans, he said, but it requires a more inclusive approach to politics and a greater focus on voter registration.

“It’s a painstaking process, but Democrats have found that worthwhile and we should, too,” Sandberg said. “You have to spend the money and time.”

One X factor going into November is the participation of so-called “inactive voters.” While these Colorado residents still can vote, they will not get mail ballots and they comprise a much smaller segment of the electorate compared with active voters — about 662,000 to roughly 3 million.

Unaffiliated voters are the biggest bloc of this group, to the tune of about 278,000, followed by Democrats and Republicans at 199,109 and 173,100, respectively.

Flaherty, the consultant, who is with Magellan Strategies, said neither party should expect much from this group if the 2014 election is any guide.

“On June 1, 2014, there were a total of 651,697 inactive voters registered in Colorado. Among those voters, only 45,293 voted in the 2014 general election — a turnout rate of 7 percent,” he wrote in a recent blog post. “While that rate may end up being higher in 2016 due to an increased interest in the presidential election, it is clear that inactive voters can hardly be considered as likely voters.”