By Greg Giroux, CQ Staff

A worsening political environment for Republicans and a massive infusion of cash from the Democratic Party are causing CQ Politics to change the ratings in two dozen congressional races, all in the Democrats’ favor.

Recruiting and funding candidates in dozens of House districts — many of which had not been competitive partisan battlefields in years — is a continuation of the Democrats’ strategy from 2006, when the party made a net gain of 30 House seats to capture the majority.

The Democratic Congressional Campaign Committee (DCCC), which is engineering the party’s effort to grow its majority this year, expanded its efforts to put Republican-held seats in play — and recent political developments and just-filed campaign finance reports indicate that the strategy is producing a bounty of contested races that exceeds the expectations of many Democratic optimists.

The race ratings changes should not necessarily be interpreted as a prediction of huge Democratic gains on Election Day. In most cases, these contests are still rated as either “Leans Republican,” a highly competitive category that indicates that the GOP still is slightly favored to win, or “Republican Favored,” a mildly competitive category. But these races nonetheless appear increasingly competitive, with upsets at least a plausible possibility. And even if few of them do produce party turnovers, this expanded list of serious challenges may force the cash-strapped National Republican Congressional Committee (NRCC) to play more defense in the waning days of the election, diminishing the resources they would rather use to help capture Democratic-held seats.

The two dozen race rating changes will be described in two separate stories. This first installment covers eight contests in the Midwestern states of Illinois, Indiana, Iowa, Minnesota and Nebraska. Please consult CQ Politics tomorrow for explanations of the rest of the race rating changes.

• Illinois’ 14th (New Rating: Democrat Favored. Previous Rating: Leans Democratic). Seven months ago, Democrat Bill Foster’s win in a special election reverberated in the political world because Foster, a physicist and first-time candidate for political office, defeated Republican businessman Jim Oberweis in this west-of-Chicago district that was the political base of former Republican House Speaker J. Dennis Hastert . But the rematch between the two men doesn’t appear highly competitive, in part because Illinois Democrat Barack Obama is his party’s presidential nominee and in part because Oberweis’ loss to Foster this spring was his fourth unsuccessful try for a major political office in Illinois in the past six years (Oberweis also lost campaigns for governor in 2006 and for senator in 2002 and 2004). The generic Republican lean of Illinois’ 14th mitigates against a runaway victory by Foster, but he should win more convincingly than the five-point margin by which he beat Oberweis in March.

• Indiana’s 2nd (New Rating: Safe Democratic. Previous Rating: Democrat Favored). CQ Politics had kept this race in “Democrat Favored” because Rep. Joe Donnelly is seeking re-election for the first time in a district that had backed President Bush in 2004 and twice elected Republican Chris Chocola, whom Donnelly unseated in 2006. But Donnelly has amassed one of the most conservative voting records for a House Democrat, and his Republican opponent, businessman Luke Puckett, doesn’t appear to be enough of a threat to keep this race on the watch list. It also helps Donnelly that Barack Obama is polling competitively in Indiana — and by extension in the 2nd District, which includes parts of north-central Indiana that aren’t all that far away from Obama’s hometown of Chicago.

• Indiana’s 3rd (New Rating: Leans Republican. Previous Rating: Republican Favored). Republican strategists are concerned about Souder, even though he represents a strongly Republican-leaning district in northeastern Indiana that takes in Fort Wayne and territory to the north and west of that city. The Democrats also see an opening, and the DCCC this week began airing a television advertisement attacking Souder. Their ad was aired independently of the Democratic campaign of Michael Montagano, a lawyer who reported spending $590,000 through the end of September. He will almost certainly spend more than 2006 Democratic nominee Thomas Hayhurt, who laid out $708,000 on a campaign that netted a respectable 46 percent of the vote. Montagano should get a late injection of campaign funds now that he’s been added to the Democrats’ “Red to Blue” list of party candidates who are waging competitive campaigns in Republican-held districts. Souder should still win, but this race is close.

• Indiana’s 7th (New Rating: Safe Democratic. Previous Rating: Democrat Favored). CQ Politics never thought Democratic Rep. Andre D. Carson was in any political danger, but kept this race on the fringe of the mildly competitive “Democrat Favored” contests because he was elected in March to succeed his late grandmother, Democrat Julia Carson . But Andre Carson seems assured of a blowout victory, in part because the original Republican nominee was replaced by a lesser-known candidate who hasn’t raised much money. Barack Obama should easily clear 60 percent of the vote in this district where Democratic Sen. John Kerry took 58 percent two years ago. Carson probably will do the same.

• Indiana’s 8th (New Rating: Safe Democratic. Previous Rating: Democrat Favored). Two years after trouncing six-term Republican Rep. John Hostettler, Democratic Rep. Brad Ellsworth seems headed for a dominant victory against Greg Goode, a former congressional aide.

• Iowa’s 4th (New Rating: Republican Favored. Previous Rating: Safe Republican). CQ Politics long weighed whether to move seven-term Republican Rep. Tom Latham out of the “Safe Republican” column. Democrats have praised the longshot campaign of Becky Greenwald, a Democratic activist who has a marketing background. Obama’s popularity in Iowa could help her in a district that four years ago narrowly backed the re-election of President Bush. Greenwald reported raising $308,000 in this year’s third quarter, a very respectable total.

But it’s difficult to envision Latham losing. The congressman is the only Iowan on the influential Appropriations Committee. The Democrats last aggressively challenged Latham in 2002, when he turned back a well-funded challenge from John Norris, a former Iowa Democratic chairman and congressional aide. Greenwald will not be as well-funded as Norris then or Latham in this campaign, but she’s running in a Democratic-friendly year. A recent endorsement from EMILY’s List and the DCCC’s Red to Blue imprimatur should give her access to some late campaign cash.

• Minnesota’s 1st. (New Rating: Democrat Favored. Previous Rating: Leans Democratic). A scuffle between Republican state Sen. Dick Day and Brian Davis, an oncologist from Mayo Clinic in Rochester who emerged as the GOP nominee, drew attention to the race for this district in the southern part of the state. But freshman Democrat Tim Walz appears to be holding his own.