More than 70 people were arrested Wednesday as members of the Occupy DC movement, joined by other demonstrators from across America, protested in the center of Washington.

It is the second mass arrest of protesters in the US capital this week, after police detained 31 Occupy DC supporters at their campsite in McPherson Square on Sunday.

At Wednesday’s protest several hundred people converged on K Street, close to the White House and the location of many Washington lobbying firms. Chanting, “We are the 99 percent,” scores of marchers sat down or formed human chains to block busy intersections.

DC police arrested 62 demonstrators on K Street, charging them with obstructing a public highway. An additional 12 people were detained a few hours later for sitting on the steps of the US Supreme Court.

Protesters told local media that they were opposed to the domination of corporate interests in politics. “K Street is the place to be if you’re going to stop the moneybags who are corrupting our government,” one demonstrator from Tennessee told the Washington Post.

Another protester, Natalie Atwater, 20, from Texas, told the paper, “Getting arrested will make people think: ‘These people care enough to be arrested? This must matter.’ ”

The Occupy protesters were joined by hundreds of people who converged on DC this week under the banner “Take Back the Capitol,” an initiative of pro-Democratic Party group MoveOn.org and the Service Employees International Union (SEIU).

The “Take Back the Capitol” campaign has involved several small direct action protests, including delivering messages to congressional offices to demand that congressmen “represent the 99 percent” and other sit-ins in public spaces. On Thursday, the campaign came to a conclusion with what its web site called a “national prayer vigil with unemployed folks and faith leaders.”

The intervention of the trade unions and various pseudo-left organizations associated with the Democrats poses a direct threat to the Occupy movement. Both MoveOn.Org and the SEIU hope to divert the mass hostility to the capitalist system and its two big business parties, which has found initial expression in the Occupy protests, and channel it into support for the Democratic Party, ultimately in an effort to re-elect Barack Obama in 2012.

On Wednesday, the day of the arrests on K Street, the SEIU’s web site proudly announced that the union still endorsed Obama in next year’s election, “As part of a broader ‘99 percent’ strategy to create good jobs now, end devastating cuts to Medicare and Medicaid and require everyone to pay their fair share.”

This, while the Obama administration rams through the biggest spending cuts in living memory, while local governments across the US respond to social protests with mass arrests and riot police.

Indicating the close relationship between “Take Back the Capitol” organizers and the political establishment, the Democratic Party delegate for the District of Columbia, Eleanor Holmes Norton, visited their camp on the National Mall Tuesday. Holmes Norton, who has sat in Congress for over 20 years, told the crowd it was “time to take back the People’s House for the people.”

Such appeals from the bought-and-paid-for representatives of big business must be rejected.

The Occupy movement marks only an opening phase of a new period of mass social struggles. However, the union bureaucracies and the professional charlatans of the bourgeois “left” want it to be a high-water mark of opposition, limited to protests and appeals to the political establishment.

To the extent that the Occupy movement retains its “no politics” stance, it cannot break with capitalism and the political status quo. The fight against the dictates of the banks and corporations can be taken forward only by the working class on the basis of its political independence from the Democrats and their hangers-on, in a struggle for socialist internationalism.