The severity of the climb back to the majority facing House Democrats could be summed up in one fundraising report filed this week: veteran Rep. John Tierney’s.

Tierney, who is embroiled in his wife’s family’s legal troubles, has been outraised for the past three quarters. The Massachusetts Democrat’s latest fundraising report showed that he ended June with $693,000 in cash on hand, compared with the $802,000 his Republican opponent had in the bank.

Tierney’s situation is indicative of a broader problem for House Democrats, whose “Drive to 25” campaign is complicated by a handful of races that should be safe or are considered prime pickup opportunities.

Troubled incumbents and the potential for flawed general election candidates in these five or six contests will force the party to spend valuable resources needed elsewhere to net the 25 seats that would put Democrats back in power.

“It’s not helpful, and we wish that wasn’t the case,” a senior Democratic Hill staffer said.

At the top of the list are Tierney and Rep. David Cicilline (R.I.), two embattled incumbents in very Democratic states and in otherwise safe districts. Both face top-tier Republican recruits in November.

Cicilline was previously the mayor of Providence, and the city’s financial straits have dogged him since the beginning of his Congressional term.

Democrats remain confident they will keep both seats despite the incumbents’ vulnerabilities.

“Overwhelming Democratic districts vote for Democrats — especially in a presidential election year — and there’s nothing in these races that lets Republicans win districts that voted around 60 percent for President Obama,” a national Democratic operative said.

But holding the seats will come at a high price — TV ad time in Boston and Providence is very expensive.

The Democratic Congressional Campaign Committee and House Majority PAC have reserved a combined $5.6 million in ad time in the Boston market. The market includes Tierney’s district but also covers two competitive races in New Hampshire.

“As Mitt Romney is finding out, any time you’re on the defensive, you’re losing ground,” Democratic fundraiser Michael Fraioli said. “When you lose ground, you spend money whether it’s radio or TV or in the mail or changing your schedule to shore up whatever the problem is.”

Both parties face races and nominees that become unexpected headaches each cycle. But with a lack of an obvious political wave this year, Democrats have to hold and win many more seats than Republicans do, with little room for error.

Democrats are quick to counter that the GOP has a bevy of weak candidates and incumbents, many of whom won in the 2010 wave with similar re-election obstacles. The Republican problems are legitimate and will cost money and time.

Aside from defending troubled incumbents in safe seats, upcoming primaries and runoffs could also complicate Democrats’ math.

Rep. Francisco “Quico” Canseco (R-Texas) is one of the most vulnerable incumbents in the country, and Democrats are bullish on their recruit, state Rep. Pete Gallego. But there is a realistic chance he might not make it through the July 31 runoff with former Rep. Ciro Rodriguez, who has consistently raised fractions of Gallego’s quarterly fundraising hauls.

Some Democrats wonder if the DCCC will even compete for the seat if Rodriguez is the nominee.

“We’ve all been down the road with Ciro before,” the senior Hill staffer said. “I think Ciro is great in a safe Democratic seat. But Ciro does not have a good track record in a swing seat in a tough year. And he’s got a lot of voting baggage from our time in the majority.”

Others insist the seat is still in play with Rodriguez, who carries sizable name identification and voter familiarity from his tenure in Congress.

In other primaries, outside groups could be the determining factor even though the candidates they are backing may be problematic nominees.

Former Arizona state Sen. Kyrsten Sinema and Connecticut state Speaker Chris Donovan could prove to be two of those candidates.

Sinema is an Arizona political star with a smart team and EMILY’s List behind her, but she has a 10-year record of public statements that local Democrats worry do not fit the new tossup 9th district. The statements have already surfaced in her three-way primary, and the GOP has made clear that her liberal record will be fair game if she is the nominee in the fall.  

For Donovan, an FBI sting resulting in the arrest of his finance director has sent his campaign into turmoil. He has not been implicated, but his fundraising dropped below $100,000 in the second quarter. Former state Rep. Elizabeth Esty, one of the other Democrats running in the open-seat race, posted a strong second quarter, and some party strategists are hoping she will emerge as the nominee. Still, organized labor has doubled down on Donovan, and that support could pull him through the primary.

In both races, the DCCC has shown no hint of a preferred candidate, but local Democrats have shown concern about the prospect of either as the nominee.

Party strategists remain hopeful about the overall House landscape, even if they get the less desirable nominees.

“There are such things as flawed candidates, but it doesn’t mean they’re going to lose,” a national strategist said.