The Department of Health and Human Services is suggesting that politicians visiting the U.S.-Mexico border are slowing down family reunifications – and U.S. Rep. Mike Coffman thinks that accusation is absurd.

“I think that HHS is already trying to insulate itself by blaming members of Congress for its failures,” the Aurora Republican said Thursday. “Raising concerns about the cost of HHS staff time, involved in responding to congressional visits to the border, is ridiculous. Oversight of the executive branch is the constitutional responsibility of members of Congress.”

Coffman is among the Colorado politicos who have visited the border amid the controversy over the separation of children from parents seized by authorities. Others have included Colorado House Speaker Crisanta Duran and U.S. Rep. Diana DeGette, both Democrats from Denver.

“If I had more confidence in the ability for this administration to unite these families then there would be no need for me to have visited a detention center at the border,” Coffman added. “The problem is that based on what I’ve seen, I absolutely don’t have that confidence, so I will continue to personally be involved in making sure that these families are reunited.”

> RELATED: HHS: Congressional visits to migrants wasting resources

Matthew Bassett, the HHS assistant secretary for legislation, sent a letter to chairs of the House and Senate judiciary committees, saying the visits by politicians had “created resource constraints that are threatening to impact (the Office of Refugee Resettlement’s) ability to quickly reunite the children in our care with a parent or safely place them with a sponsor.”

Melania Trump, the first lady, has made two visits to the border.

Coffman’s response to HHS comes after he sent a letter this week to President Donald Trump urging him to put a military general in charge of  reunifying parents and children separated by authorities as they sought to get into the U.S.

About 2,000 children have been separated from their parents as part of the Trump administration’s “zero tolerance” policy at the border, which began in April. After a political and humanitarian outcry, Trump signed an executive order to allow undocumented families to remain together, although how that will work is unclear.

Coffman has been critical of the policy and the pace at which families have been reunified, calling it a “human rights mess.”

The issue puts Coffman on the same side as House Minority Leader Nancy Pelosi, a Democrat from San Francisco.

“Congressional oversight of this matter has already been proven to be critical in ensuring that the Administration’s constant abuses are held in check,” Pelosi said, according to CNN.