In April, Rep. Michael Grimm (R-N.Y.) was indicted on 20 counts of tax and business fraud. It was a pivotal moment that moved Grimm's already-up-for-grabs seat substantially closer to Democrats' grasp.

Today, the independent expenditure arm of the Democratic Congressional Campaign Committee went on the air with its first two midterm campaign TV ads. One commercial seeks to remind voters that Grimm is embroiled in a legal fight. The DCCC really rubs it by including footage of Grimm threatening a television news reporter after President Obama's State of the Union address.

So, why prioritize hitting a bruised candidate ahead of a slate of other, more competitive contests? The ad says two things.

One is that Democrats don't feel that former New York City councilman Domenic Recchia (D) has Grimm's seat in the bag. They wouldn't spend money going after Grimm -- who has a lot of loyalty in his district -- if they did.

Obama won 52 percent of the vote against Mitt Romney in Grimm's district. The nonpartisan Cook Political Report rates the race as "Lean Democratic." But the DCCC is telegraphing that it sees a closer contest than numbers and handicappers suggest.

The second thing the ad says is that scandals are often much more politically explosive in the moment than they are down the road. The charges, which relate to a restaurant owned by the congressman, were all over the news in the spring, both nationally and in Grimm's Staten Island-based district. But the coverage has subsided. That's where attack dogs like the DCCC come in to remind people about what they might have forgotten.

As I wrote last week about scandals surrounding Sen. John Walsh (D-Mont.) and Rep. Scott DesJarlais (R-Tenn.), the more time that passes between a scandal and an election, the better the chances a politician can survive.

The DCCC also launched an ad Tuesday hitting Republican Tom MacArthur, who is vying for the seat of retiring Rep. Jon Runyan (R-N.J.). Burlington County Freeholder Aimee Belgard is the Democratic nominee.

The National Republican Congressional Committee, meanwhile, started running an ad against Democratic attorney Gwen Graham, who is challenging Rep. Steve Southerland (R-Fla.).

Republicans see Democrats' decision to spend money attacking Grimm as a sign the national climate, in which President Obama's approval ratings have plunged to record lows, is hurting Democrats even in districts they should be picking up.

Grimm is still an underdog. But what Democrats just demonstrated is he should not be written off completely just yet. They clearly haven't done that.