Diving into yet another high-profile clash with the Bush administration, House Oversight and Government Reform Chairman Henry Waxman (D-Calif.) threatened Tuesday to subpoena current and former White House officials over the alleged mishandling of classified data.

In a June 26 letter to White House counsel Fred Fielding, Waxman said if he did not receive a prompt response to two-month-old requests for interviews, he would subpoena on Thursday White House Director of the Office of Administration Alan Swendiman, former White House security officer Mark Frownfelter and ex-White House Security Office Director Jeff Thompson.

But Democratic committee aides were hopeful on Tuesday that Fielding and the White House would comply in some fashion, preventing a legal standoff. One GOP committee aide said Democrats were now willing to allow the attorneys for witnesses to be present at committee interviews, which makes voluntary compliance more likely.

For the moment anyway, the California Democrat is avoiding a similar standoff over the testimony of White House Chief of Staff Andrew Card, who Waxman threatened to subpoena in April about the White House’s handling of classified information. Fielding at the time declined to offer Card’s testimony, citing executive privilege.

The subpoena possibility coincides with another deadline for the White House to release documents to the House and Senate Judiciary committees related to the controversy over the firing of U.S. attorneys. Both committees ordered the White House, and former Political Director Sara Taylor, to turn over documents related to the inquiry by June 28. It is unclear whether that will happen at this point.

Waxman first made the allegations of improper handling of classified information after a March 16 hearing about the outing of former CIA officer Valerie Plame. But they gained new traction this week with news that Vice President Cheney had refused to comply with an executive order regulating the care of classified documents.

But Waxman contends that the breach of regulations is more widespread than ignoring the authority of the National Archives’ Information Security Oversight Office and involves the president as well as the vice president’s office.

“There is evidence that both the White House and the Office of the Vice President have flaunted multiple requirements for protecting classified information,” Waxman writes.

The California Democrat, who is spearheading various probes into the administration, adds that current and former White House security personnel have contacted the committee and related “dangerously inadequate” practices with respect to “investigating security violations, taking corrective action following breaches and physically securing classified data.”

Independent of the Information Security Oversight Office, there are three entities, according to the White House, that govern classified information treatment inside the White House: the White House Security Office, the National Security Council and the White House Military Office.

But according to Waxman, in a break with previous norms, all but the most senior White House Security Office personnel have been barred from carrying out unannounced inspections of White House offices. Waxman also alleges that Security Office personnel have ignored breaches reported to them by Secret Service and CIA officers — including a case in which classified information was left in a foreign hotel room by a White House official during a presidential trip, and reports that White House personnel left classified information out on their desks instead of in secure locations. The officers told the committee that no one was investigated or disciplined in these incidents.

In the letter, Waxman also blasts the renewal of presidential aide Karl Rove’s security clearance given his role in the Plame affair. And he cites reports of poor management by former White House Security Office Director James Knodell and Deputy Director Ken Greeson, who allegedly brought their BlackBerrys and cell phones into secure locations in violation of security rules.

White House spokesman Tony Fratto said Tuesday that an executive order governs the handling of classified White House documents and that all White House staff authorized to handle such data “are trained on the appropriate procedures.”

“The president and the White House staff take the issue of document security seriously and take measures to ensure that classified documents are handled appropriately,” Fratto contended.

Earlier in the day, White House spokesman Tony Snow — who had not seen the Waxman letter — said breaches have been reported and acted upon by the Information Security Oversight Office.

According to Waxman, security officers who contacted his committee reported a “systemic breakdown” in procedures for responding to reports of security violations.

“According to the security officers, the practice within the the White House Security Office was not to document or investigate violations occurring in the West Wing or to take corrective action,” Waxman writes.

The most high-profile of these, Waxman contends, was the failure of the White House to initiate its own probe into the leak of Plame’s identity.

The broadside on regulations regarding classified data is just the latest in a barrage of inquiries launched by Waxman’s committee into the White House.

Other current investigations by Waxman include White House contacts with jailed lobbyist Jack Abramoff; the use of Republican National Committee e-mails by White House staff including Rove; and White House use of pre-Iraq War Intelligence.