A week of obstacles is threatening Republican plans to seize control of Congress in the upcoming midterm elections.

On Tuesday, President Obama will hold his first major mega-rally since the 2008 presidential campaign.

The mass rally is likely to draw tens of thousands to the campus of the University of Wisconsin in Madison and is expected to help generate the kind of national energy that galvanized progressive forces during the 2008 elections. In addition, thousands will gather at hundreds of watch parties nationwide. The crowd could well outsize any of the demonstrations the tea party groups have been able to pull together.

At the end of the week, on Oct. 2, a Washington demonstration expected to draw well over 100,000 people will almost surely dwarf last month’s rally by Glenn Beck and the tea baggers. The more than 300 organizations sponsoring the march hope to turn the national conversation itself away from the tea party and toward the fights for jobs and justice.

Groups sponsoring the march, including the AFL-CIO, the NAACP, and the National Council of La Raza, are determined to make the point that the tea party fringe does not speak for America’s working people.

500 buses carrying 25,000 people have already been filled in New York-by just one union local, SEIU Local 1199.

George Gresham, president of the health care workers local, said, “We are getting a voice out there that really speaks for working people, a voice that respects the diversity of this country, which the tea party does not.”

Many sponsoring the march have attacked the Republicans in Congress for blocking progressive approaches to fixing the economy. Labor blames Senate Republicans for holding up job creation programs and is focused on defeating those Republicans on Election Day.

Marchers will call for extension of jobless benefits, better wages, labor law reform, massive spending on green jobs, better public education and immigration reform. The rally will give Democrats loud and clear backing for legislation that would implement those demands.

And while many unionists will be attending the march, even more of their brothers and sisters will go door-to-door in neighborhoods across the country, campaigning in key districts.

Other bad news this week for the GOP is a growing investigation by the press into a secretive campaign organization run by Bush administration mastermind Karl Rove.

A story in the Los Angeles Times reveals that an entire secret network has been funneling many millions of dollars into Republican campaigns across the country. The network, which aims at electing Republicans to Congress, uses legal loopholes allowing wealthy donors to conceal their identities.

A Pew Research Center survey conducted last week constitutes the fourth bit of bad news for the Republicans. According to the poll, poor performance by the party in the Northeast may turn out to be a key factor in preventing it from taking over the Congress in November.

The Pew survey finds that while Democrats trail Republicans by three points among all registered voters in the South, they are ahead of the GOP by nine points in the Northeast.

It is only because of a so-called “enthusiasm gap,” the survey says, that the GOP seems to be doing better among those who are, at the moment, most likely to vote.

Since 2006, Democrats have taken 18 northeastern seats away from the Republicans, with their strongest gains in New England. Among the region’s 22 House members, not one is Republican.

Despite chances to pick up two seats in New Hampshire and one in Massachusetts, Rep. Dan Maffei, an upstate New York Democrat elected in 2008, told the Washington Post yesterday that the Republicans’ right-wing image, shaped by the tea party, will prevent a GOP comeback in his region, and therefore nationally.