WASHINGTON—A handful of tough ads levied by Republican groups this week have forced Democrats onto the defensive as they look to repel the GOP attempts to define them.

Those ads, and their responses, headline another busy week in the world of campaign advertising. Check this week's YouTube playlist of the ads that caught the eye of the NBC News Political Unit, and read on for more on each spot.

CLF and Randy Bryce in Wisconsin 01

Complicated family dynamics are common in everyday life, but it's rare to have a family member actively campaigning against a congressional candidate. That's exactly what's happening in Wisconsin, where Democrat Randy Bryce's brother joined the Congressional Leadership Fund in a new ad that blisters the Democrat for being anti-cop and directly asks voters to back the Republican candidate.

The group has also run ads needling Bryce on his arrest record, and the Democrat's campaign released a direct-to-camera ad in response where Randy Bryce acknowledges his past "mistakes" and argues that he understands the "hardships" his would-be constituents face.

Rep. Bryan Fitzpatrick and Scott Wallace in Pennsylvania 01

Republican groups have been hammering away at philanthropist Scott Wallace, the Democrat, in the hopes of disqualifying him through opposition-research dumps on donations from his family foundation. Now the Republican's campaign is getting in on the exercise with a harsh ad that attempts to build a juxtaposition between Fitzpatrick's FBI service (as well as his great uncle, a police officer who died in the line of duty) and Wallace's donations to a group that gave sympathetic news coverage to a man convicted of killing a police officer.

This charge has been a regular line of attack for Republicans looking to effectively label Wallace as sympathetic to cop-killers for the donation to Democracy Now!, even though Wallace's foundation is independent from the group's editorial process. Wallace's new spot in response calls the accusation "Fox News smears that have been called false" and includes a local sheriff defending Wallace's record on criminal justice.

Democratic Congressional Campaign Committee in Colorado 06

Remember when Colorado Republican Rep. Mike Coffman made waves with a 2016 ad where he promised to "stand up" to Donald Trump if he was elected president? The DCCC does too, and they're using it in a new spot that claims Coffman hasn't held up to his end of the bargain.

The spot hits Coffman on his voting record, accusing him of being in lock step with Trump and for jeopardizing health care for his vote to back the GOP tax cuts. Coffman's camp called the characterization a "lie" in a statement to NBC News, with allies noting he refused to support the GOP's final plan to repeal and replace the Affordable Care Act.

National Republican Congressional Committee in New Mexico 02

This ad is the NRCC's version of "lions, tigers and bears, oh my!" Except in this case, it's more like: "Antifa, Bernie Sanders, Alexandria Ocasio Cortez, Elizabeth Warren and Nancy Pelosi, oh my!"

The new attack ad links Democrat Xochitl Torres Small to what it frames as an "extremist" left pushing an agenda of "criticizing law enforcement, pushing massive tax hikes...a total government takeover of health care." The ad comes days after the release of two interesting polls in this GOP-leaning district—one showing Republican Yvette Herrell up 7 points and another showing Torres Small up 1 point.

It's also another one where Republicans link a Democrat to government-run health care when the candidate hasn't gone that far (the arguments from GOP groups have been carefully worded guilt-by-association attacks).

Bill Schuette in Michigan Governor

There's been one big story in Michigan this year—the devastating revelations surrounding former USA Gymnastics and Michigan State University physician Larry Nassar's widespread pattern of sexual abuse. Schuette, the Republican Attorney General whose office prosecuted Nassar, is up with a new ad with a Nassar victim's parents applauding his work on the case.

Joe Cunningham in South Carolina 01

If Cunningham wants to turn a seat that President Trump won by more than 12 points in 2016 red, he'll need a whole lot of Republicans. That's exactly who he's targeting in a new spot that quotes Republican elected officials explaining why they support him.

Patients for Affordable Drugs Action in ME-02

Democrats continue to share personal health care stories in their quest to take advantage of poll after poll showing health care a major issue for voters in the midterms. And it's not just campaigns—this progressive group is out with a new, seven-figure spot with a mother and her diabetic son, with the mother criticizing Republican Rep. Bruce Poliquin on health care.