Washington CNN  — 

More than a week after subpoenaing former Donald Trump aide Dan Scavino to cooperate with its investigation into the January 6 riot at the US Capitol, the House select committee investigating the attack has been unable to physically serve the subpoena to him, according to multiple sources familiar with the effort.

The news comes just days before the committee’s deadline for Scavino and three other close allies of the former President to comply with subpoenas requesting documents by October 7 and a deposition by October 15.

Scavino, Trump’s former White House deputy chief of staff, did not respond to CNN’s request for comment. One source familiar with the situation joked that the committee should just tweet the subpoena to the former Trump aide since he’s been actively trolling the panel there in recent days.

The other Trump aides who have been subpoenaed include former Trump White House chief of staff Mark Meadows, former adviser Steve Bannon and Kash Patel, a former chief of staff to then-acting Secretary of Defense Christopher Miller.

Patel has acknowledged he’s received the committee’s subpoena. It appears that the committee has been successful in their attempts to serve subpoenas to the other two Trump allies.

In their letter to Scavino, the committee outlines that because of his close proximity and long history of working with the former President, he can provide useful information regarding conversations Trump had on January 5 about trying to convince members of Congress to not certify the election, the former President’s movements on January 6, and the broader communication strategy the White House had in the lead up to the January 6 rally.

The committee is also preparing for the eventuality that some of Trump’s allies will refuse to comply with the subpoenas. Among the options the panel is weighing to compel their cooperation is the threat of holding them in criminal contempt.

At the same time, Trump and those in his orbit who are likely considered to be witnesses in the committee’s probe have offered little indication they have coalesced around a broader legal strategy – whether that be some combination of the former president invoking executive privilege, resisting the subpoenas in an effort to run out the clock or pleading the 5th.

While Trump threatened more than a month ago to invoke executive privilege to block the committee’s earlier request for records, several people close to the former president have told CNN in recent days that they are not aware of a legal strategy taking shape since then.

CNN reached out to a dozen lawyers who have represented or advised Trump in the past, but either they did not respond or weren’t willing to be interviewed. One attorney, John Eastman, would only say that if he were representing Trump in this matter, it would be a violation of attorney-client privilege to say so.

Doug Collins, a former congressman, has been representing Trump on these matters before other committees this summer, but has not responded to CNN’s repeated requests for comment.

Republican Rep. Adam Kinzinger, one of two GOP members serving on the select panel, told CNN’s Jim Sciutto the committee is “going to do everything in our power to get them to testify.”

“I mean, there is civil, there is criminal referrals that can happen if they refuse, refusing a subpoena from congress is a crime. We aren’t out to try to hang this around anybody’s neck. We want answers,” he said.

“The problem is when you start seeing people resist, and people obfuscate, you have to look at that and go why are they doing that if they have nothing to hide? We have a lot of people coming and talking to us voluntarily. We’ll get to the bottom of it. We want to do it quickly, efficiently and thoroughly,” he added.

CNN’s Paula Reid contributed to this report