The sudden closeness of the New Jersey Senate race is the latest sign Democrats are fighting an uphill battle to capture the upper chamber majority despite a midterm election cycle largely driven by discontent with President Trump.

While Sen. Bob Menendez, D-N.J., still holds a 6.5-point advantage in the RealClearPolitics polling average, the last two polls have him up just 5 points over Republican challenger Bob Hugin. Menendez is below 50 percent, a crucial threshold for an incumbent, in the most recent one. The nonpartisan Cook Political Report shifted the race to “toss-up” on Friday.

“The question has always been whether or not enough New Jerseyans can vote for a Republican in Trump’s first midterm,” said Republican strategist Mike DuHaime, who advised former Republican Gov. Chris Christie. “We haven’t won a U.S. Senate race here in 46 years, so is it possible to break that streak when the political headwinds are historically so strong?”

Like Texas for the Democrats, New Jersey has been a tease for Republicans before. GOP nominee Doug Forrester looked like he was going to unseat ethically challenged Democratic Sen. Robert Torricelli, until Democrats plucked Sen. Frank Lautenberg out of retirement. Forrester remained competitive but ultimately lost by 10 points.

Then, in late October 2004, there was a poll showing President George W. Bush in a dead heat with Democratic challenger John Kerry in New Jersey, buoyed by his post-9/11 leadership. Bush did receive a bounce, especially in the New York City suburbs, but Kerry kept the Garden State blue with just under 53 percent of the vote to Bush’s 46 percent.

A few polls even showed Trump closing to within single digits in New Jersey in the final weeks of his 2016 campaign against Hillary Clinton. Clinton ended up winning by 12.8 points.

Unlike Texas Democrats, however, Republicans do occasionally break through in New Jersey. Christie and Christine Todd Whitman were both two-term governors. There have been GOP majorities in the state legislature. Hugin has been looking at Menendez’s ethics and past legal troubles as an opening, at the very least forcing Democrats to commit resources to what should be a safe seat while playing defense in multiple battleground states.

[Also read: New Jersey paper endorses Democrat Menendez in 'depressing choice' between 'two awful candidates']

“Regardless of the result in New Jersey, the national money coming to NJ to bolster Menendez against Hugin’s spending is a very big win as it helps Republicans retain the majority,” said DuHaime. “Any dollar spent here defending a seat in a safely blue state is one less dollar defending embattled Democrat incumbents in places like Missouri, North Dakota, Missouri, and Indiana.”

Democrats face a tough path in the Senate despite otherwise favorable political conditions because they are defending so many more seats than the Republicans and have 10 incumbents seeking re-election in states Trump carried, including several of the above where the president won decisively and remains popular.

The super PAC affiliated with Senate Minority Leader Chuck Schumer, D-N.Y., has spent more money in New Jersey than on pickup opportunities in Tennessee or Arizona and defending vulnerable red-state incumbents in North Dakota, West Virginia, and Montana. Senate Majority PAC is reportedly planning to sink another $2.8 million into the Menendez race.

“We’d be in a much better position with a different candidate [than Menendez], but this is where we are,” conceded a Democratic operative who requested anonymity to speak candidly. “We’ll still pull it out, it’s just harder than it has to be.”

After he was acquitted on some charges, the Justice Department dropped its corruption case against Menendez earlier this year. Menendez vowed to avenge himself against politicians, especially Democrats, who left him for dead when he was first charged: “To those who were digging my political grave so they could jump into my seat, I know who you are and I won't forget you.”

“Hugin has tried to make the race a referendum on Menendez,” DuHaime said. “Menendez has tried to make the race a referendum on Trump. It is a tight race. Hugin has been very aggressive. He’s spending a ton of money and campaigning in areas that traditionally vote heavily Democratic.”

We’ll find out whose strategy is right next Tuesday.