Washington (CNN) -- It gets second billing to the race for the White House, but the battle for control of the Senate is just as important and fresh polling suggests Democrats in some crucial contests are on the rise.
A Republican tidal wave in the 2010 midterms gave the GOP control of the House of Representatives. They also reduced their deficit in the Senate and set their sights on retaking that chamber this year.
Democrats currently control the Senate, 53-47 -- down from 59-41 before the midterms -- but they're defending 23 (21 Democrats and two independents who caucus with the party) of the 33 seats up for grabs in November.
While the GOP still has a very good chance of winning control, which they lost in the 2006 midterms, their path to victory might be getting a bit more difficult.
"Democrats are cautiously optimistic. We inherited a difficult map but Republican missteps and strong Democratic campaigns have made a major difference," Democratic Senatorial Campaign Committee Communications Director Matt Canter told CNN. "There is still a long way to go but right now the tide is certainly moving in our favor.
Republicans remain confident but agree that it's way too early to be making predictions.
"The Senate Democrats' reckless and failed leadership on the economy has put them on defense in races across the country and Republicans are positioned to hold them accountable on Election Day," Brian Walsh, Canter's counterpart at the National Republican Senatorial Committee, said. "But seven weeks is an eternity in politics and no one in either party should be taking anything for granted."
Let's start with Massachusetts, one of the most expensive and closely watched Senate contests this cycle. Polls over the past year suggested that the marquee matchup between incumbent Republican Sen. Scott Brown and Democratic candidate Elizabeth Warren was a dead heat. That changed earlier this week with Warren's numbers rising in two new surveys of likely voters in the Bay State.
Warren held a 48%-44% margin over Brown in a Suffolk University/7News poll and a 50%-44% advantage in a Western New England University survey. Both margins are within the polls' sampling errors.
Warren's well received speech earlier this month at the Democratic convention may have contributed to her rise in the surveys. But another new poll, by UMass Lowell/Boston Herald, gives Brown a 49%-45% edge.
Before launching her campaign for the Senate last year, Warren was best known as a top adviser to President Barack Obama, a role in which she was integral to the formation of the Consumer Financial Protection Bureau, which was created as part of the 2010 financial reform law.
Brown was a state lawmaker who scored an upset victory in a January 2010 special election to fill the final 2 1/2 years of the term of the late Democratic Sen. Ted Kennedy.
Brown and Warren faced off Thursday in the first of four debates leading up to the election.
There was also a debate on Thursday in another high-profile and expensive Senate race in Virginia.
It's a similar story as Massachusetts, with polls over the past year showing a tie between the Democrat, former Gov. Tim Kaine (who most recently served as chairman of the Democratic National Committee) and former Gov. George Allen, who's trying to win back the Senate seat he lost in the 2006 election to Democrat Jim Webb, who decided against running for re-election.
But a pair of polls out this week from The Washington Post and from Quinnipiac University/CBS News/New York Times indicate Kaine with leads of seven and eight points. A new Fox News poll has it closer, with Kaine holding a four-point edge.
Two Democratic incumbents facing what were thought to be tough re-elections are seeing good news in the latest polling. Sen. Sherrod Brown of Ohio holds a seven-point lead over Ohio state Treasurer Josh Mandell, the GOP candidate, in two surveys over the past two weeks.
And Sen. Bill Nelson of Florida holds 14-point leads over Rep. Connie Mack Jr. in two surveys released over the same span. The polling indicates that both Brown and Nelson so far are holding their own against of flood of attack ads put up by pro-Republican independent groups.
In Wisconsin, where four-term Democratic Sen. Herb Kohl is retiring, a new poll suggests that Rep. Tammy Baldwin, who's trying to keep the seat in party hands, is up nine points over former Republican Gov. Tommy Thompson, who served in President George W. Bush's Cabinet. But another survey indicates the race tied at 47% each.
And some new polling suggests that Democratic Sen. Debbie Stabenow of Michigan is building a lead as she faces off against former Rep. Pete Hoekstra, the Republican candidate.
Meanwhile Democratic chances in Senate contests in Indiana and North Dakota also seem to be on the rise, while Republican chances of grabbing back a seat in traditionally blue Connecticut seem much better now than just a few weeks ago.
The race for the White House influences down-ballot races, and President Barack Obama may be helping Democratic candidates in Senate contests in some battleground states.
Thompson blamed his numbers, in part, on GOP presidential nominee Mitt Romney's rocky campaign.
"The presidential thing is bound to have an impact on every election," Thompson told Madison television station WKOW. "You know, whether you're a Democrat or Republican, if your standard-bearer for the presidency is not doing well, it's going to reflect on the down-ballot."
But while the face-off between Obama and Romney greatly impacts the other contests, the candidates will determine them.
"Candidates and campaigns matter," says Jessica Taylor, senior analyst and reporter for the non-partisan Rothenberg Political Report. "Several candidates are still going to need to run significantly ahead of their party's presidential nominee in more hostile states, and while that playing field may level out closer to Election Day, candidates such as Joe Donnelly (Democrat in Indiana), Heidi Heitkamp (Democrat in North Dakota) and Linda McMahon (Republican in Connecticut) have been running strong campaigns and appear to be benefiting from weaknesses by their opponents."
With 6 1/2 weeks to go, Democrats may be breathing a little bit easier.
CNN's Peter Hamby contributed to this report