President Donald Trumps longtime aide and former White House communications director Hope Hicks will not respond to any questions about her tenure in the White House in an interview with the House Judiciary Committee, frustrating many Democrats eager for information.

White House attorneys have informed Democratic House leaders that Hicks will not be answering any inquiries about her time in the White House, claiming that as she was a top Trump aide she is immune under executive privilege. This assertion has outraged Democrats, whose attempts to investigate the president’s potential obstruction of justice have been repeatedly thwarted by the White House’s legal team. It is expected that the Democrats will challenge this strategy in court, hoping to legally enforce the subpoena against Hicks. The House has been forced to go through the judiciary system to compel testimony from several other White House officials, such as former White House Counsel Donald McGahn.

While Hicks will not be speaking about her time in the White House, she will be discussing her time on Trump’s campaign, which is not covered by executive privilege. Members of the House Judiciary Committee hope that she will provide new information on Trump’s purported hush-money payment to several women who accused him of various indecencies. This strategy indicates that the Democrats are widening their probe to include more than just Russian collusion and obstruction of former Special Counsel Robert Mueller‘s investigation, signaling that the Democrats hope to gain a wider variety of information as they decide whether or not to begin formal impeachment proceedings.

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Hicks’ appearance before the House panel is the first time that a member of Trump’s inner circle will testify as part of the probe, as the White House has done, and continues to do, everything in its power to prevent witnesses from speaking. The president himself has repeatedly denied the legitimacy of the investigations into him, attempting to cast a shadow of doubt on the intentions of House Democrats. Many observers question why the White House is so desperate to prevent the testimony of Trump’s close allies if there truly is nothing to hide, especially as the president’s legal requests verge increasingly closer to autocratic.