The Republican chairman of a House panel is accusing President Barack Obama of either obscuring his involvement in the failed Fast and Furious gun-tracking program or improperly invoking executive privilege.

Rep. Darrell Issa, R-Calif., chairman of the House Committee on Oversight and Government Reform, made the accusations in a letter to the president released Tuesday.

The letter marks the latest salvo in a months-long investigation that has already ensared Attorney General Eric Holder, who could on Thursday become the first sitting attorney general held in contempt by the House of Representatives. Issa's committee voted last week along party lines to recommend the contempt vote before the full House.

Issa recently subpoeanaed Holder in an effort to obtain more documents detailing Fast and Furious, a program in which federal agents allowed firearms to flow to Mexican drug cartels in an attempt to locate the end users, but then lost track of the weapons. After unsuccessfully attempting to negotiate an eleventh-hour deal, Holder asked Obama to intervene and use his executive privilege to block the documents from being released.

For the first time in his presidency, Obama invoked executive privilege. The White House defended the move by pointing to a longstanding precedent of shielding internal deliberations from public exposure.

Our position is consistent with executive-branch legal precedent for the past three decades spanning administrations of both parties, spokesman Eric Schultz said in a statement, adding that the courts have routinely considered deliberative process privilege claims and affirmed the right of the executive branch to invoke the privilege even when White House documents are not involved.

But Issa is not satisfied by that claim. In his letter, he renewed his suggestion that knowledge of Fast and Furious extended to the highest levels of government.

Either you or your most senior advisers were involved in managing Operation Fast and Furious and the fallout from it ... or you are asserting a presidential power that you know to be unjustified solely for the purpose of further obstructing a congressional investigation, he wrote.

Because the Justice Department maintains that the documents do not implicate the White House, Issa wrote, the Justice Department personnel involved in writing the documents lack the operational proximity to the president necessary to justify executive privilege. He wrote that providing the documents could avert the impending contempt vote.

I still believe that a settlement, rendering further contempt of Congress proceedings unnecessary, is in the best interests of the Justice Department, Congress, and those most directly affected by Operation Fast and Furious, Issa wrote.