White House acting chief of staff Mick Mulvaney. Photo: Cheriss May/NurPhoto via Getty Images

White House acting chief of staff Mick Mulvaney instructed a former security clearance official not to testify before the House Oversight Committee, according to letters sent to panel chairman Elijah Cummings Monday, and first obtained by ABC News.

The big picture: Former White House Personnel Security Director Carl Kline was to testify before the committee Tuesday, after the panel voted to subpoena him in its White House security clearance investigation.

Details: In the White House letter, Michael Purpura, deputy counsel to President Trump, wrote Kline was instructed not to appear after the committee rejected a White House request for an Office of Counsel of the President representative to attend the deposition.

What they're saying: Kline's lawyer wrote a letter stating they wished to answer the "legitimate legislative questions of this committee, but [were] warned of impending conflict."

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Commission rejects Trump campaign request for 4th debate

President Trump in Cleveland, Ohio on August 6. Photo: Jim Watson/AFP via Getty Images

The Commission on Presidential Debates on Thursday denied the Trump campaign's request to add a fourth debate in the first week of September or move up one of the existing debates in order to get ahead of an expected surge in early voting.

The bottom line: Trump and former Vice President Joe Biden are set to debate on Sept. 29 in Cleveland, Oct. 15 in Miami, and Oct. 22 in Nashville. "If the candidates were to agree that they wished to add to that schedule, the Commission would consider that request," the organization wrote in a statement.

Updated 43 mins ago - Politics & Policy

Coronavirus dashboard

Illustration: Eniola Odetunde/Axios

  1. Global: Total confirmed cases as of 2:30 p.m. ET: 18,895,712 — Total deaths: 710,110— Total recoveries — 11,402,427Map.
  2. U.S.: Total confirmed cases as of 2:30 p.m. ET: 4,852,749 — Total deaths: 159,407 — Total recoveries: 1,577,851 — Total tests: 58,920,975Map.
  3. Politics: Pelosi rips GOP: "Perhaps you mistook them for somebody who gives a damn" — Ohio Gov. Mike DeWine tests positive.
  4. Public health: Fauci says task force will examine aerosolized spread.
  5. Business: The health care sector imploded in Q2More farmers are declaring bankruptcyJuly's jobs report could be an inflection point for the recovery.
  6. Sports: Where college football's biggest conferences stand on playing.

Ohio Gov. Mike DeWine tests positive for coronavirus ahead of Trump visit

Photo: Justin Merriman/Getty Images

Ohio Gov. Mike DeWine (R) has tested positive for COVID-19 and plans to quarantine at his home for the next 14 days, his office announced Thursday. He currently has no symptoms.

Why it matters: The 73-year-old DeWine was set to meet President Trump Thursday on the tarmac at an airport in Cleveland and was tested as part of standard protocol. He is the second governor known to have contracted the coronavirus, after Oklahoma Gov. Kevin Stitt (R).