WASHINGTON — When President Obama faces Congress and the nation on Wednesday, he will be in the uncomfortable position of looking too much like a lame duck with three years left on his term.

Some of the reasons are in Roxbury, Mass. It was for votes in neighborhoods like Roxbury, called “the heart of black culture in Boston,” that Obama campaigned to save the Senate candidacy of Democrat Martha Coakley.

The turnout in one Roxbury district was 34 percent, pretty good for Buffalo. The trouble was that the turnout in white towns like Topsfield, Boxford and Rockport was 72 percent or better.

The numbers in the victory of Republican Sen.-elect Scott Brown, as in the GOP victories in Virginia and New Jersey last November, strongly suggest that Obama has squandered his base, and that he himself could be politically

radioactive. This possibility mocks Obama’s effort to force Gov. David

A. Paterson, a fellow African- American, into the ditch last September, claiming Paterson could pull down Democratic prospects in the statewide elections this fall.

Democratic defeats in three states had three elements in common: Obama’s advisers were reluctant to put his prestige on the line, his entry excited white independents and Republicans against him, and his minority base went limp.

That African-Americans are hurting more than any others in the economic downturn has been known for a year or more. But last December, the Congressional Black Caucus went public with its criticisms of his disinterest.

CBC Chairwoman Barbara Lee, D-Calif., reminded Obama of his campaign promise to address the plight of African-Americans whose unemployment rate is almost double that of whites. Still living in his bubble, Obama quickly rejected the CBC’s complaint, saying it would be wrong of him to focus just on the needs of black people.

Obama still plays well with some white elites in Cambridge, Mass., where many wore black armbands on Wednesday. There aren’t enough of them, though, to outweigh the disenchanted who thought we were going to get out of Iraq and Afghanistan, have “transparency” in government and drive the lobbyists from the temple.

Instead, Obama tripled our armed forces in Afghanistan. Defense Secretary Robert Gates told Afghan and Pakistani leaders just last week we are “in there for the long haul.”

So are the lobbyists, who wrote the abortive health care bill that Obama and congressional Democrats took into secret sessions. Special interests of the chic variety also wrote the cap-and-trade and card labor bills, both of which are also now deader than the Spirit of Christmas Past.

In his address, Obama is not likely to ruminate about his radical attorney general’s practice of reading captured al-Qaida operatives their Miranda rights, or trying terrorists in lower Manhattan.

But events will force Obama’s attention on the economy. There, too, Obama is trapped. He and the Democratic Congress have already blown $787 billion in “stimulus” money, too much of it flushed down the sewer in bailouts for state and municipal payrolls and pensions.

And because he’s watched over by free-trade types like economics czar Lawrence Summers, Treasury Secretary “Honest Tim” Geithner and trade ambassador Ron Kirk, Obama is likely to follow the inspiration of President Bill Clinton and continue letting Communist China take our factories across the Pacific.

So the state of the union message read by a weakened president who has produced next to nothing in his first year will be long on slogans and more promises, and little olive branches for Republicans. For those still inclined to believe what he says, the televised speech will be exciting to watch.

Yet many Democrats in his immediate audience in the House chamber will be thinking of Brown and wondering, “will I be next?”