It happens every cycle: an entrenched, unassuming House incumbent loses re-election to a primary rival.

Who will be this cycle’s first victim? At least five vulnerable House incumbents are already engaged in electoral battles with a party challenger. Three Republicans and two Democratic upstarts have organized early efforts to boot these House members from office.

To be sure, these challenges are not indicative of a widespread anti-incumbency fervor in 2014. Polling shows Congress with low marks from voters, but there are a relatively small number of competitive races this cycle. That’s mostly thanks to the decennial redraw of congressional districts ahead of the 2012 cycle.

CQ Roll Call selected these five primaries — in no particular order — to watch based mostly on circumstances specific to each incumbent. These members share one thing in common: If they are not careful, they may end up on Roll Call’s Casualty List.

Michigan’s 11th

Incumbent: Republican Rep. Kerry Bentivolio (1st term)

Primary: Aug. 5, 2014

Primary challenger: attorney David Trott

Rothenberg Political Report/Roll Call race rating: Republican Favored

A former reindeer rancher, Santa Claus impersonator and veteran, Bentivolio made headlines recently for public comments about impeaching the president. Like his background, his path to Congress was anything but typical: When Rep. Thaddeus McCotter’s re-election signature petitions proved faulty in 2012, Bentivolio remained the only Republican on the ballot. He won the seat and has a target on his back ever since.

Last week, Trott — who boasts significant financial resources — announced he would challenge the libertarian freshman. Republicans in this suburban and exurban Detroit district hail from the party’s more moderate and business-friendly wing, giving Trott an advantage with the Oakland County political pooh-bahs.

But Trott comes with his own baggage as a foreclosure lawyer in the Detroit area. Still, Democrats privately concede they would rather face Bentivolio in the general election.

Bentivolio continues to have the backing of House GOP leadership, which helped him raise much-needed cash over the August recess. They’re likely interested in this race because the district could be competitive if the GOP nominee falters — although the composition leans Republican.

Idaho’s 2nd

Incumbent: Republican Rep. Mike Simpson (8th term)

Primary: May 20, 2014

Primary challenger: attorney Bryan Smith

Race rating: Safe Republican

Earlier this cycle, Simpson — one of Speaker John A. Boehner’s top House allies — drew the ire of the conservative Club for Growth as one of its first incumbent targets. Soon after, in July, the group backed Smith in its first candidate endorsement of the cycle.

Just two months into the race, both campaigns have attacked each other in back-and-forth radio buys. Smith’s camp accuses Simpson of being “liberal,” while Simpson’s ads and team calls Smith a “personal injury lawyer.” Both campaigns vigorously dispute the other’s characterizations.

Simpson has friends in high places — Boehner traveled to Idaho to attend a fundraiser for the incumbent during recess. It’s money Simpson will need for his first tough race in many cycles.

The good news for Republicans? The primary will not likely affect the outcome of the general election. This eastern Idaho, agriculture-based district is a safe GOP seat.

Massachusetts’ 6th

Incumbent: Democratic Rep. John F. Tierney (9th term)

Primary: Sept. 16, 2014

Primary challenger: attorney and former Marine Seth Moulton

Race rating: Lean Democrat

An ethics inquiry into Tierney’s and his wife’s personal finances — which was just dismissed by the Ethics Committee — and slim margin of victory last cycle make him a top target for both parties in 2014. Republicans and Democrats (at least privately) say they did not expect Tierney to survive last cycle, but he squeaked out a victory thanks to high party turnout in the Bay State.

On paper, Moulton makes for a formidable primary challenger. But Marisa DeFranco, an attorney who lost a 2012 primary to now-Sen. Elizabeth Warren, is also running and could spoil the race for Moulton by shaving off some of the anti-Tierney vote.

In the general, Republicans expect former state Sen. Richard Tisei to run against Tierney again, after losing to the congressman by a single point last cycle. Republicans are confident this cycle because they do not expect Warren’s top-tier Senate race to drive turnout down the ticket.

The primary’s outcome could affect the general election, too. In fact, some Democrats privately confess the party has a better shot at holding the seat if Tierney loses in the primary to Moulton.

California’s 17th

Incumbent: Democratic Rep. Michael M. Honda (7th term)

Primary: June 3, 2014

Primary challenger: attorney Ro Khanna

Race rating: Safe Democrat

Honda starts his race as the front-runner thanks to high name recognition in a district he’s represented for more than a decade. But Khanna has assembled almost everything he needs to give Honda the challenge of his political lifetime.

Khanna boasts a campaign team filled with former aides to President Barack Obama, the support of many wealthy business leaders in California’s Silicon Valley and more than $1.7 million in the bank going into the race.

Honda has the support of almost the entire California congressional delegation, many Asian-American leaders and Obama.

To be clear, this race is technically not a primary. In California, candidates run in a jungle primary in which the top two vote-getters, regardless of party, move on to the general election. It’s likely that Honda and Khanna will face off in June, then again as the top two candidates on the November ballot.

This is a heavily Democratic district that Obama carried with 72 percent.

Tennessee’s 4th

Incumbent: Republican Rep. Scott DesJarlais (2nd term)

Primary: Aug. 7, 2014

Primary challenger: state Sen. Jim Tracy

Race rating: Safe Republican

Talk about baggage. DesJarlais is still dogged by 2012 allegations that he encouraged his wife and a mistress to have multiple abortions. A recent report showed DesJarlais also carried on affairs with multiple patients and co-workers and was fined for the behavior earlier this year.

To make matters more serious for DesJarlais, his top opponent is an experienced politician. Tracy has more than $650,000 in the bank — compared with DesJarlais’ paltry $88,000 in cash on hand. The numbers cast serious doubt whether DesJarlais can even be competitive in the primary — let alone win it.

Tracy got more good news last month, when the other GOP competitor, state Rep. Joe Carr, dropped his DesJarlais challenge in favor of running for Senate.

Now DesJarlais’ detractors have just one choice in the primary, which handicappers say almost assures the two-term member won’t make it through to the general election this cycle.

Luckily for Republicans, Tennessee’s 4th is one of the strongest GOP districts in the country. Whoever emerges from the Republican primary will win in the general.