(CNN) Republicans are riding a wave of optimism into the closing week of the fall campaign, eyeing seats far deeper into Democratic terrain than party leaders imagined only weeks ago, with rising GOP confidence of winning a strong House majority amid signs that critical Senate seats are also increasingly within their grasp.
Democratic House candidates in competitive seats from California to Connecticut are scrambling to fight against a torrent of voter discontent over the economy, inflation and crime that could upend the balance of power for the second half of President Joe Biden's first term.
If the divisive midterm election finishes as a referendum on the Biden agenda -- rather than a stark contrast with the polices and posture of Republicans -- Democrats are bracing for the prospect of a bruising Election Day that could reshape the political order in Washington.
The President, who is set to campaign this week far away from most of biggest Senate battlegrounds given his tepid approval ratings, implored Americans to carefully weigh their options and consider what Republican control of the House, and potentially the Senate, would mean.
"This is a fundamental choice," Biden said after casting his early ballot this weekend in Delaware. "A choice between two very different visions for the country."
The question is whether even some of the very voters who supported Biden two years ago are still open to hearing his message.
To amplify the point and in hopes of motivating their supporters, Democrats are turning to former President Barack Obama, who delivered a pointed closing argument at weekend stops in Georgia, Michigan and Wisconsin.
"Inflation is a real problem right now," Obama said, noting economic challenges around the world in the aftermath of the Covid-19 pandemic. "The question you should be asking is, who is actually going to do something about it? The Republicans talk a lot about it, but what is their answer?"
With Republicans in a strong position to capture the House -- an outcome the White House has quietly started to prepare for -- the battle for control of the Senate is the searing focal point of the final eight days of the race.
Democratic incumbents in Georgia, Arizona and Nevada are on the defensive in exceedingly close contests with their GOP challengers, while Republicans feel far more bullish about defending an open seat in Pennsylvania and holding onto Wisconsin and an open seat in North Carolina. The GOP needs a net gain of just one seat to win the majority.
"This is our year," Florida Sen. Rick Scott, chairman of the National Republican Senatorial Committee, said Sunday on CNN, predicting his party would win "52 plus" seats.
One of the biggest uncertainties looming in several of those top battlegrounds, party officials and strategists tell CNN, is whether voters are in the mood to deliver split-ticket verdicts in contests for governor and Senate or whether coattails from the top of the ticket could pull candidates over the finish line.
In Georgia, GOP optimism in the Senate candidacy of Herschel Walker is boosted by the strength of Republican Gov. Brian Kemp's reelection bid. The Senate race with Democratic incumbent Raphael Warnock will be decided by a runoff election on December 6 if neither candidate surpasses 50% of the vote next week.
In Ohio, party officials say they are far less nervous about J.D. Vance and his campaign with Democratic Rep. Tim Ryan because Republican Gov. Mike DeWine has maintained a robust lead in his bid for a second term.
In Arizona, party officials acknowledge that Republican Senate nominee Blake Masters would not be locked in a tight race with Democratic Sen. Mark Kelly if GOP gubernatorial nominee Kari Lake were not firing up conservatives in her strong campaign against Democrat Katie Hobbs.
A chief case study is unfolding in Pennsylvania, where Josh Shapiro, the state's Democratic attorney general running for governor, is in a commanding position in his race against Republican Doug Mastriano, whose candidacy has been all but abandoned by GOP leaders.
Whether Shapiro can lift Democrat John Fetterman's Senate candidacy -- or whether voters decide to cross party lines and support Republican Mehmet Oz -- will be among the most anticipated questions on election night. In the general election, Oz has sought to cast himself as a moderate, a clear pivot after winning the primary with the endorsement of former President Donald Trump.
"Washington keeps getting it wrong with extreme positions," Oz said in a debate last week, pledging to bring civility and compromise to the Senate, as Fetterman is trying to cast his rival as extreme, particularly on abortion.
While those are among the most closely watched Senate contests, a sour political environment has left almost no Democratic senator on the ballot immune to vigorous challenges by Republicans. From Sens. Patty Murray in Washington to Michael Bennet in Colorado to Maggie Hassan in New Hampshire, even incumbents in a second tier of competitive races are fighting far tougher races than they anticipated a year ago.
Top Democratic leaders do not dispute the assertion that challenging economic headwinds are coursing through their party, but they argue voters will still be animated by calls to protect abortion rights in the wake of the Supreme Court's late June decision overturning Roe v. Wade.
Protecting democracy also remains a galvanizing argument for some voters, with so many prominent GOP nominees promoting denials and conspiracy theories about the 2020 election results.
For Biden, who is scheduled to travel this week to Florida, New Mexico, Maryland and Pennsylvania, the November 8 election marks the 50th anniversary of winning his first Senate race in Delaware. Since 1972, he has had a front-row seat to the highs and lows of Election Day, which history shows is almost always unkind to the party in power.
Since World War II, the president's party has lost an average of 28 House seats in a president's first midterm election, according to the American Presidency Project. With Democrats holding only a five-seat edge in the House, even going against the grain of history could mean losing control of the chamber.
In the first national campaign since Trump attempted to overturn his 2020 defeat and inspired baseless questions about election integrity, it remains an open question the degree to which history is still a reliable guide.
With nearly 21 million Americans having already cast their ballots across 46 states, Democrats at the White House and in Congress concede their urgent burden is trying to change the trajectory of the race in the final eight days in hopes of slowing Republican momentum.
As he explained the stakes of the election in a speech Friday evening in Philadelphia, the President minced no words, saying: "It's going to shape what this country looks like for next decade or more -- not a joke."