At least 400 Christian leaders will travel to Capitol Hill next week to lobby senators against the nomination of Chuck Hagel for secretary of defense, pro-Israel group Christians United for Israel (CUFI) announced Wednesday.

The delegation has nearly doubled in size since the emergency lobbying call, CUFI officials said, according to the Washington Free Beacon.

“The response to our call to attend this emergency summit has been overwhelming,” CUFI executive director David Brog told the Free Beacon. “We initially hoped that we could get 200 Christian leaders to fly in last minute. But we’ve already registered 400 leaders, and the calls are still coming in.”

The group will reportedly meet with representatives of all 100 Senate offices to express opposition to Hagel’s nomination, which CUFI says would endanger the national security of the United States and Israel.

“This will be very impactful for Republicans and Democrats from states with large evangelical populations like Tennessee, North Carolina, Arkansas, and Louisiana,” said one GOP Senate aide. “Republicans will know the Hagel issue is a key issue for the base while Democrats in Republican-leaning states may think twice before walking the plank for a nominee they never wanted.”

CUFI, the largest pro-Israel organization in the country, has been one of the most vocal pro-Israel groups fighting Hagel’s nomination. 

Hagel has, in the past, boasted that he is not intimidated by the “Jewish lobby.” His critics pointed out that the pro-Israel lobby includes many evangelical Christians, like those who make up CUFI.