But the strategy has shifted as conservative insurgents who were once given little chance of success achieved a string of stunning victories, defeating establishment-backed Republicans in primary contests. The new Democratic strategy is to portray Republican candidates as extreme, fringe, radical captives of the political phenomenon known as the tea party.
Initially underestimated as a loose-knit band of malcontents and ideologues, the tea-party movement has gained significant momentum and gone national. Democrats have seized upon some of the more outlandish comments of candidates associated with the movement in an effort to convince voters that their ideas are narrow and destructive.
If little changes in the polls, it's likely that the campaigns will turn harsher and uglier. Discussion of issues will be perfunctory at best. The focus will be on personal flaws and dark warnings about dangerous and extreme views.
The problem for Democrats is that, at least so far, this strategy has had minimal impact. Polls and predictions by academics and longtime operatives of both parties continue to foretell significant Republican gains, with perhaps as many as 50 seats changing hands.
The widespread discontent and restiveness that helped Barack Obama achieve victory nearly two years ago has escalated to a boiling anger as the distressed economy lingers, unemployment continues to hover near 10 percent, home foreclosures swell, and the national debt climbs to an unprecedented level. The perception is that little has improved even as government spending has soared.
In such an environment, the party in power is held accountable.
The president has pleaded for understanding and patience, but the American people don't seem inclined to give him either one. With some 20 months in office, he can no longer blame his predecessor, and he hasn't yet been able to deliver on the "hope and change" promise that was the centerpiece of his campaign.
Even his administration's signature achievement - the overhaul of the nation's health-care system - has become enmeshed in controversy and sharply conflicting interpretations of its impact. Some 60 percent of Americans now think it was a bad idea.
To his credit, President Obama has placed himself on the front lines of his party's effort to retain control of Congress. He argues that while his policies have not yet fully taken hold, the nation will be better off when they do. The problems the country faces did not develop overnight and will not be solved overnight, he says, and Republicans offer only obstructionism.
But it's a hard sell to convince deeply unhappy people that the party in power - the presumed source of the unhappiness - should be given the opportunity to continue in power. The desire for instant gratification is always present in politics, and the tendency seems especially pronounced this year.
The tea-party message of less spending, lower taxes, and less intrusive government has resonance. To the surprise of most and the chagrin of many, it has attained traction, drawing strength from disaffected voters frightened about their futures and concerned about the direction of the country.
There can be no doubt that change is in the air in 2010 - just as it was in 2008. The only question is how deeply the desire for it runs.
Carl Golden is a senior contributing analyst with the William J. Hughes Center for Public Policy at Stockton College.