A steely, stocky Air Force veteran, who says little but sees Israel's Menachem Begin as odious and the Arab world as Egypt's natural friend, has been maneuvering into an ever-stronger position as eventual successor to President Anwar Sadat.
The open question for many Cairo diplomats and political analysts is whether or not the heir apparent, Vice-President Hosni Mubarak, may have become too apparently heir, overplaying his hand with a President reputedly allergic to potential rivals.
"Hosni has never been stronger," says an Egyptian who has worked closely with Mr. Mubarak, "but I would also say he will now have to tread very carefully. Visibility isn't always a good thing in Egyptian politics, even if it is achieved with the President's apparent support."
Until recently, Mr. Mubarak had been anything but visible. But last week he spent five days in Washington, conferring with top American officials.
A surprise vice-presidential choice in April 1975 over at least several more highly placed military and civilian candidates, the taciturn Air Force commander from the 1973 war became something of a smiling shadow next to the energetic Mr. Sadat.
"The laughing cow," Mr. Mubarak was promptly dubbed by street-corner humor, borrowing the trademark of the bland French cheese on Cairo grocery shelves.
Egypt's Vice-President does not laugh easily. To make the metaphor stick, you'd have to find a very shrewd and determined cow.
Hosni Mubarak, it can no longer be doubted, is a powerful man.
He was one architect -- and a prime victor -- in Egypt's mid-May Cabinet reshuffle, for him the culmination of a slow, sure march from invisibility.
It was a march made in Anwar Sadat's footsteps and with Anwar Sadat's help.
"Sadat's Sadat," Mr. Mubarak was initially known to senior diplomats and other Cairo political analysts, a reference to Mr. Sadat's own quiet but powerful role under the late radical Egyptian President Gamal Abdul Nasser before succeeding him in 1970.
When Mr. Sadat took over, the analysts who make their living from such things predicted he would not last long. "It was a mistake to underestimate Sadat," one Western ambassador commented recently. "It would be just as great a mistake to underestimate Mubarak . . . . If indeed he succeeds Sadat, my guess is the Vice-President will prove very forceful and very durable."
The relationship between the two men is close. Both hail from large village families in the Nile delta province of Menoufeia. As mutual associates tell it, President Sadat first met an ambitious young Air Force officer named Hosni Mubarak at a military base in the Sinai Desert city of El Arish in the early 1950s.
The two hit it off quickly. Mr. Sadat, soon to figure among the "free officers" who spearheaded the 1952 overthrow of the Egyptian monarchy, is said to have jotted Mr. Mubarak's name down in a notebook.
Some two decades later, the memory came in handy. Looking for a trusted officer to handle the air wing of Egypt's 1973 recapture of the Israeli-held Suez Canal, Mr. Sadat settled on Hosni Mubarak.
Shortly afterward, Mr. Sadat plucked him out of the military and charged him with infusing the No. 2 position in Egyptian government with "the spirit of 1973 ."
At first, Mr. Mubarak was indeed "Sadat's Sadat." Whether by design or coincidence, he was rarely in the public eye, virtually never on Egyptian air waves. He did fill in for Mr. Sadat on missions abroad, notably aping Henry Kissinger's shuttle diplomacy in heading off war between Algeria and Morocco in the mid- 1970s.
But basically, Mr. Mubarak seemed a professional presidential accessory.
What independent power he amassed or exercised, he amassed and exercised behind the scenes.
That power was considerable, and through a mixture of inertia and political shrewdness Mr. Mubarak has now edged very close to center stage.
From the start, he played on physical proximity to Mr. Sadat. The Vice-President sat in, if silently, on most high-level meetings. He sometimes chaired discussions within Mr. Sadat's ruling political apparatus. With a brief from the President to keep politics out of the barracks, Mr. Mubarak also consolidated relations with the military.
It was Mr. Mubarak who undertook the "consultations" leading to formation of the new Egyptian Cabinet in early May. It was Mr. Mubarak who formally announced the makeup of the new team.
"If I'm not present at a Cabinet meeting and Vice-President Mubarak is," Mr. Sadat told the new Cabinet and the nation in a milestone televised session May 19, "he is automatically the chairman."
The message of recent speeches by Mr. Sadat seems clear: The President plans to stay in power for the foreseeable future, helped by a constitutional amendment permitting indefinite tenure, but Mr. Mubarak is the man to watch as eventual successor.
Mr. Mubarak's publicly expressed views are Mr. Sadat's. But friends and associates of the Vice-President hint at important differences between the two men.
Mr. Sadat does not like the details of day-to-day government. Mr. Mubarak, it is said, thrives on them.
Mr. Sadat tends to make major political decisions on a lonely pinnacle of power. Mr. Mubarak, associates say, depends greatly on trusted aides.