The junior senator from across the river has made it official: He’s resigning from office this weekend, leaving Illinois with only senator for the time being.

As our Springfield bureau chief Kevin McDermott reports this afternoon, Barack Obama announced that he will resign from the U.S. Senate effective Sunday.

Something about another job opportunity?

In any case, speculation for who Gov. Rod Blagojevich will appoint continues to focus on U.S. Rep. Jesse Jackson Jr., scion of the civil rights leader, and Illinois Secretary of State Jesse White.

Meanwhile, the pressure to be a one-man delegation falls to veteran Democrat Sen. Dick Durbin, who’s probably happy to take on the challenge since it means having a friend on Pennsylvania Avenue.