Republicans fear the party could blow a golden opportunity to pad its 51-49 Senate majority after watching a collection of underwhelming candidates emerge as the likely nominees in key contests.

The Republican Party entered the 2018 cycle threatening incumbent Democrats in 10 states that President Trump carried in 2016. Even as immediate dissatisfaction with Trump quickly threatened the Republican majority in the House, a favorable map acted to shield the GOP from similar headwinds in the Senate.

Seven months before Election Day, Republicans are worrying about dwindling opportunities as candidates that are some combination of defective, unimpressive and underfunded appear headed toward victory in a handful of GOP primaries.

“It’s definitely not like the class of candidates from 2014,” said a Republican strategist, who, like the more than half-dozen GOP operatives interviewed for this story, requested anonymity in order to speak candidly about the party’s Senate candidates.

Senate Republicans won the majority in 2014 after eight years in the minority, flipping nine seats, and nearly two more, on the strength of a stellar recruiting class. In 2016, Senate Republicans held the majority, as targeted incumbents fielded strong campaigns that outpaced Democratic challengers and buffered them from volatility at the top of the ticket.

The party has its share of good Senate recruits this cycle in targeted Democratic seats: Rep. Kevin Cramer in North Dakota; state Attorney General Josh Hawley in Missouri; Army combat veteran and businessman John James in Michigan; Gov. Rick Scott in Florida. Minimal resistance to their nomination is expected — if any.

But in other promising races, including in states where Trump’s job approval ratings are solid, the field of primary candidates has left some GOP insiders unenthused. Republicans are monitoring primaries in Montana, Ohio, and Wisconsin before passing final judgment; they’re bullish on Indiana regardless, although they describe that more as an “indictment” of vulnerable Democratic Sen. Joe Donnelly.

Conditions are even worse in Pennsylvania and West Virginia, two states that have strong concentrations of Trump voters. In Pennsylvania, Republicans have all but written off Rep. Lou Barletta, who is challenging Sen. Bob Casey, D-Pa., and they have a huge problem in West Virginia — one that could put the state out of reach.

Trump won West Virginia by more than 40 percentage points and he sports an 60-plus percent approval rating there, making Sen. Joe Manchin, D-W.Va., extraordinarily vulnerable. But none of it matters if mining executive Don Blankenship wins the Republican nomination over Rep. Evan Jenkins and state Attorney General Patrick Morrissey.

Blankenship was convicted in federal court two years ago of conspiring to violate mine safety standards in an explosion that left 29 West Virginia coal miners dead. No matter; with superior resources and anti-establishment credentials, he could win the May 8 primary.

“If that guy gets the nomination forget contesting that seat. It’s like Sharron Angle and Christine O’Donnell all over again.” a Republican operative with West Virginia ties said. This individual was referring to 2010 Senate races the GOP lost in Nevada and Delaware.

Angle, in Nevada, and O’Donnell, in Delaware, were flawed candidates with minimal general election appeal. Each lost a race considered eminently winnable in what turned out to be a GOP wave year. Angle and O’Donnell managed to win their respective primaries because their sharp rhetoric and anti-establishment credentials swayed Republican primary voters.

Republicans are worried that too many weak candidates, especially in an election cycle shaping up as a backlash against their leadership in Washington, could jeopardize the party’s prospects of maximizing potential gains, despite a map of contested seats that tilts in their favor. Republicans also could find themselves defending as many as four seats.

Some Republican strategists dissent from their anxious colleagues. Republican primary voters, they say, are looking for authenticity and aggressiveness. The usual resume that would describe a GOP candidate as top tier — accomplished, well spoken, genteel — no longer applies, and won’t motivate base turnout in November.

That’s an important factor to consider with Democrats enjoying a yawning enthusiasm gap over Republicans as the midterm draws nearer.

“The Republican Party has moved. Everyone wants to look at Trump like he’s an outlier — he’s not an outlier,” one veteran Republican strategist said. “The Republican primary voter doesn’t like the same old, buttoned-up politician bullshit. That’s over; it’s not going to happen anymore.”

The GOP’s candidate recruiting issues are complicated. There isn’t necessarily much the party could have done to avoid them

The party was all set with top tier picks in Montana and Ohio. Then Trump tapped then-Rep. Ryan Zinke, R-Mont., to serve as Interior secretary, and Ohio Treasurer Josh Mandel was forced to exit the Senate race to attend to his wife’s health issues. And in these and other states, the bench was thin without them, though not empty.

In Montana, Democratic Sen. Jon Tester could still face a tough fight against one of the two likely GOP nominees, businessman Troy Downing or state Auditor Matt Rosendale. The same might also be the case for Democratic Sen. Tammy Baldwin in Wisconsin, where state Sen. Leah Vukmir and Iraq War veteran Kevin Nicholson, a former Democrat, are running for the Republicans.

Meanwhile, Trump’s choice to replace Mandel in Ohio was Rep. Jim Renacci, and he answered the president’s call when it came. Of course, first he must get through banker Mike Gibbons, who is trying to run as the heir to Trump — an outsider businessman.

Disclosure: The author’s wife is an adviser to Rick Scott.