A lackluster performance in three of Colorado strongest Republican counties – including El Paso County (Colorado Springs) – cost Republican Donald Trump Colorado’s nine electoral votes in the 2016 presidential election.

The official county votes were certified by Colorado Secretary of State Wayne Williams just prior to the Electoral College meeting that voted Trump into the White House.

Trump did well enough in El Paso, Douglas (Castle Rock) and Weld (Greeley) counties, but he needed to really sweep those three traditional centers of GOP voting power if he was going to defeat Hillary Clinton in Colorado. As a result, Clinton edged Trump out with strong Democratic support in the Denver/Boulder area.

In El Paso County, Trump received 62 percent of the two-party vote. That was down 6 percentage points from the 68 percent of the two-party vote that Republican President George W. Bush polled in El Paso County in the 2000 presidential election 16 years earlier.

El Paso County is the second most populous county in Colorado, narrowly trailing Denver. In a county with so many voters, that six percent drop in Republican support is a lot of votes.

Donald Trump’s unorthodox campaign style, filled with startling statements and criticism of other politicians, probably had something of a cooling effect on his support in highly urbanized but very conservative El Paso County.

Just to the north of El Paso County lies Douglas County, a distant suburb of Denver. Douglas County dropped its Republican percentage of the vote seven points between 2000 and 2016 – from 67 percent Republican to 60 percent Republican. Again, that kind of percentage drop in a populous county is severely damaging to a political party.

The results for the GOP were a little better in Weld County, a distant outer suburb northeast of Denver. Weld County stayed even in its support for the two Republican presidential candidates, providing 62 percent for George W. Bush in 2000 and 62 percent for Donald Trump in 2016.

The good news for the Republicans in 2016 was the dramatically increased support for Donald Trump in the rural and small-town counties of the state. Trump’s reiterated message of distrust of government and his pledge to “Make America Great Again” played unusually well in the outlying areas of Colorado. These rural and small town areas of Colorado can be broken down into four major regions:

Two populous Colorado counties switched roles in the 2016 presidential election. Pueblo County surprised by voting narrowly for Trump.  Up until 2016, Pueblo County, with its large working class population and many Hispanic voters, had been reliably Democratic. Larimer County (Fort Collins) was Republican in the early 2000s, but Larimer continued its recent shift to the Democrats by voting for Clinton in 2016.

In sum, the Republicans got increased support from rural Colorado in the 2016 presidential election. They received as good support as usual in Weld County. The weakness for Donald Trump and the GOP was in the heavily populated Republican counties of El Paso and Douglas. The Republicans will have to rev up their ground game and increase their vote output in El Paso and Douglas counties if they want to match the surging Democratic vote in Denver and start winning statewide elections in Colorado.

Cronin and Loevy are political scientists at Colorado College.