NEW YORK (CNN/Money) - A decision to call Martha Stewart before Congress could come early next week as lawmakers grow increasingly frustrated by Stewart's level of cooperation with a probe into allegations of insider trading.

A spokesman for the House Energy and Commerce Committee Chairman Billy Tauzin said that by Tuesday the panel may decide to subpoena Stewart to appear and publicly answer questions, an event that would draw huge public focus.

"We have reached the end of the road with Martha Stewart," the spokesman, Ken Johnson, said. He added that a another next step could be referral of criminal charges or dropping the case altogether.

Frustrated by what it calls Stewart's stonewalling, the panel has suggested that someone is not telling the truth about the circumstances of Stewart's sale of nearly 4,000 shares of ImClone Systems. The sale on Dec. 27th came one day before a Food and Drug Administration decision on Erbitux, ImClone's cancer drug, sent ImClone shares tumbling.

Stewart has denied having inside knowledge of the news, saying she had a long-standing agreement with her broker to sell ImClone shares when they hit a certain price.

Her ImClone sale has also attracted the attention of the Securities and Exchange Commission, which is investigating Stewart.

Johnson, the panel's spokesman, said the committee staff has to tie up a few legal loose ends before making any announcement on Stewart. They are looking over a cache of phone and e-mail records delivered by Stewart's attorney's last month.

Revealing details about a new apparent discrepancy, Johnson said Sam Waksal, the former ImClone CEO and friend of Stewart's, has said he did not talk to Stewart about the ImClone sale or any other matter between December 14, 2001 and January 5, 2002 when they met at a party in Panama.

Stewart has essentially backed up that account.

But Johnson said the committee investigators have learned of a five-minute phone call to Sam Waksal's exclusive cell phone logged on December 31, 2001 he says may have come from Stewart.

"Someone has lied to the committee," Johnson said.

Still, the call would have been made after Stewart's ImClone (IMCL: down $0.20 to $7.46, Research, Estimates) sale.

A Martha Stewart spokesperson decline comment Thursday.

The saga has taken a toll on shares of Stewart's publishing and home decor company, Martha Stewart Living Omnimedia (MSO: Research, Estimates). Its shares, which fell 17 cents to $7.63 Thursday, are down 53 percent this year.