The campaign arm of Republicans in the U.S. House of Representatives is dropping its financial support for U.S. Rep. Mike Coffman, the GOP incumbent who has represented Colorado’s battleground 6th Congressional District for five terms, Colorado Politics has confirmed.

The National Republican Congressional Committee (NRCC) is canceling $1 million in TV advertising and redirecting the spending to a swing district in the Miami area, according to a source familiar with the group’s thinking.

It’s the second major GOP funding group to abandon Coffman, who is facing a challenge from Democratic attorney Jason Crow, a first-time candidate.

At the end of September, the Congressional Leadership Fund – an organization associated with House Speaker Paul Ryan – pulled out of the district, cancelling $1 million in TV ad reservations, although the NRCC added $600,000 to its ad buy at the same time.

The contests in the suburban-Denver district have routinely been the most hotly contested and expensive congressional races in Colorado, but this year it could be among the hottest races in the country.

According to the Center for Responsive Politics, outside spending in the race is approaching $14 million, with more than a dozen outside groups spending at least six figures in the district this cycle.

Through this week, the NRCC reported spending $2.1 million in the race, compared with $2.3 million spent by its counterpart, the Democratic Congressional Campaign Committee, which supports Crow.

Officials with the NRCC still see Coffman’s seat as competitive, but are forced to make ruthless decisions about spending as Election Day nears, a source familiar with the organization’s decision told Colorado Politics.

A New York Times/Siena College poll conducted this week found Crow leading Coffman in support among likely voters by 9 percentage points, 47-38 with 9 percent undecided.

Crow led Coffman by 11 percentage points in a poll conducted by the same organizations last month, but the Coffman campaign released internal polling that showed Coffman trailing by just 2 percentage points.

“News out of Washington is never going to make or break our campaign,” a Crow campaign spokesman said in an emailed statement. “We’ve got one focus for the next 18 days: making sure every ballot in CD-6 is returned with a vote for Jason Crow in it. Until then, we’re keeping our heads down.”

Coffman’s campaign didn’t immediately respond to a request for comment.