US President Barack Obama speaks in a rare prime-time address to the nation on July 25. With the United States poised on the brink of a potential default, President Barack Obama appealed to Americans to "make your voice heard" to members of Congress.

With the United States poised on the brink of a potential default, President Barack Obama appealed to Americans to "make your voice heard" to members of Congress.

They appear to have listened.

The websites of a number of members of the House of Representatives and the Senate were sluggish or simply unavailable on Tuesday, apparently due to .

Attempts to visit the websites of several members of the House were met with the message "the site you requested is currently unavailable" while the sites of a number of , both Democrat and Republican, were slow to load.

The House switchboard sent an internal email to members of the body saying that due to "high volume of external calls" House telephone circuits were "near capacity resulting in outside callers occasionally getting busy signals."

The office of Senator Bill Nelson, a Democrat from Florida, said it had received "hundreds of calls" about the president's speech.

"Most folks just want Congress to act, and Sen. Nelson agrees," his office said in a statement. "He believes the president was right in saying both bear responsibility for running up the federal debt."

In his speech Monday night, Obama said "the American people may have voted for divided government, but they didn't vote for a dysfunctional government.

"So I'm asking you all to make your voice heard," Obama said. "If you want a balanced approach to reducing the deficit, let your member of Congress know.

"If you believe we can solve this problem through compromise, send that message."