Emperor Ping, who had had no children by his wife Empress Wang or any of his concubines, he has no heir.

Further, by this point, Emperor Ping's grandfather, Emperor Yuan, has no surviving male issue.

The progeny of Emperor Ping's great-grandfather Emperor Xuan are therefore examined as possible successors.

There are fifty-three great-grandsons of Emperor Xuan still living, but they were all adults, and Wang Mang dislikes this fact—he wants a child whom he can control.

Therefore, he declares that it is inappropriate for members of the same generation to succeed each other (even though Emperor Ping had succeeded his cousin Emperor Ai several years earlier).

He then examines the twenty-three great-great-grandsons of Emperor Xuan—all of whom are infants or toddlers.

While the examination process is proceeding, the mayor of South Chang'an submits a rock with a mysterious red writing on it—"Wang Mang, the Duke of Anhan, should be emperor."

Wang has his political allies force Grand Empress Dowager Wang to issue an edict granting him the title of "Acting Emperor", with the commission to rule as emperor until a great-great-grandson of Emperor Xuan can be selected and raised.

In the spring of 6, Acting Emperor Wang selects the child Ying—just one year old—as the designated successor to Emperor Ping, claiming that soothsayers have told him that Ying was the candidate most favored by the gods.

He gives Ying the epithet Ruzi—the same epithet that King Cheng of Zhou had when he was in his minority and under the regency of the Duke of Zhou—to claim that he is as faithful as the Duke of Zhou.

However, Emperor Ruzi does not ascend the throne, but is given the title of crown prince.

Empress Wang is given the title empress dowager.

As acting emperor, Wang reinstitutes the Zhou system of five grades of nobility—duke, marquess, earl, viscount and baron.