While the United States was quick to support the aspirations of Tunisian protesters once the government there was toppled, Egypt is a different story.
As one of only two Arab countries who recognize Israel, it plays a critical role in the Mideast peace process and is one of the United States' strongest allies, and one of the lead recipients of its foreign aid, in the region.
On Thursday, Obama reiterated the two countries close relationship, and that the he's "always said" to Mubarak that reform, both politically and economically, is essential for Egypt.
"Egypt's been an ally of ours on a lot of critical issues," Obama said. "President Mubarak has been very helpful on a range of tough issues in the Middle East. But I've always said to him that making sure that they are moving forward on reform -- political reform, economic reform -- is absolutely critical to the long-term well being of Egypt."
Mubarak was invited to the White House to help launch the latest round of Israeli-Palestinian talks last year. Egypt is also considered a regional leader, albeit fading, and a key voice in a strategically important area. Recent documents released by Wikileaks show that the United States has held a nuanced view of Mubarak's Egypt, tolerating human rights abuses and the veneer of democracy in exchange for geopolitical influence.
The U.S. government has also previously clashed with Nobel Peace Prize winner Mohammed ElBaradei, one of the country's leading voices on democracy who was reportedly placed under house arrest today.
ElBaradei returned home to Egypt Thursday after a month-long absence to join the protests.
"We are not waiting for help or assistance from the outside world," he said, in a direct swipe at the United States, accused by many here of supporting its closest Arab ally and not the people yearning for freedom. "But what I expect from the outside world is to practice what they preach, is to defend the right of the Egyptians, for their universal values: Freedom, dignity, social justice and the rule of law."
While he and the International Atomic Energy Agency jointly won the Nobel Peace Prize in 2005 for their efforts to prevent the militarization of nuclear energy programs, the Bush administration and later the Obama administration frequently clashed with ElBaradei because they believed he was watering down the UN watchdog's reports on Iran's nuclear program.
To his supporters, ElBaradei and his return to Egypt represents the best chance to galvanize a weak and diverse opposition. To his critics, he is an opportunist who has spent too much time in Vienna.
In Washington, D.C., Egyptian-American groups called on the Obama administration to condemn the Mubarak regime and stand on the side of protestors.
"There's a blood that's been shed in Egyptian streets and that blood is in our hands," said Dr. Samia Harris, vice president of the Alliance of Egyptian Americans. "Please stand by the right side of history. Stand by the Egyptian people."
ABC News' Sunlen Miller, Arlette Saenz and Sarah Wali contributed to this report.