In politics, candidates want to be on the offense, pressing their agenda and attacking opponents. But sometimes the best offense is a good defense that sets the record straight and flips the issue. Senate Minority Leader Mitch McConnell did this superbly last week, showing why he is likely to win in Kentucky in November.
His Democratic opponent, Alison Lundergan Grimes, appeared in an ad sitting with a retired miner who wanted to know why Mr. McConnell "voted to raise my Medicare costs by $6,000. How are my wife and I supposed to afford that?" He and Ms. Grimes then stared at the camera for five seconds, before Ms. Grimes said, "I don't think he's going to answer that."
He did answer, in 24 hours, in a video with clips of local and national media calling the charge "false," "misleading" and "laughable" since he didn't vote for the measure the miner cited. (It was a House proposal that never reached the Senate and wouldn't have raised the miner's Medicare costs.) The video even included footage of Ms. Grimes being pressed by Kentucky reporters to defend the ad. Then the McConnell campaign flipped the issue, reminding voters that President Obama's Affordable Care Act cut Medicare and saying that Ms. Grimes is "Obama's Kentucky candidate. Obama Needs Grimes. Kentucky Needs Mitch McConnell."
Colorado Sen. Mark Udall attacked Republican challenger Rep. Cory Gardner for supporting a 2010 referendum to give a fertilized egg rights as a person. Mr. Gardner shot back in an ad that he had later changed his mind "after I learned more from listening to all of you." He also turned the issue back on Mr. Udall, saying he "and President Obama can't relate to that." Labeling ObamaCare "a disaster," Mr. Gardner said, "Udall and Obama refused to listen" to voters about the unpopular law and ended by adding "I will listen" to the required disclaimer "I approve this message."
Iowa Republican Senate candidate Joni Ernst not only rebutted Democrat Bruce Braley's charges that she was ineffective in opposing spending by citing press reports calling his claims "false" and "misleading." She also reminded voters of Mr. Braley's insult of popular Iowa Sen. Chuck Grassley as a farmer without a law degree by saying she "approved this message because I may not have a law degree, but I've got something that Washington needs a whole lot more: Iowa values."
The adroitness of Republicans in understanding which Democratic attacks should be rebutted and how to turn the attacks to their advantage could determine who controls the Senate next year.
The GOP cannot count on 2014 being a repeat of 2010. It's not just that the Fox News Poll reported the generic ballot in June 2010 as 41% Republican, 37% Democratic but this month reported the generic ballot tied at 42%. This time Democrats understand they could lose, which they arrogantly did not in 2010. As a result they've launched an ad assault aimed at disqualifying GOP candidates early—a blitz that I predicted on this page in April.
Some Democrats also have substantially more cash. North Carolina Sen. Kay Hagan has spent the last five years raising money, giving her $8.7 million in cash, while after a contested primary, Republican Thom Tillis has $1.5 million. Money won't necessarily determine the outcome: Ms. Hagan faced the same cash disparity at this point in 2008 against Sen. Elizabeth Dole.
Democrats also are focused on getting out supporters who don't vote in midterm elections. They will get some value from these efforts, even if the model they're using from Mr. Obama's 2012 campaign failed to get out all his 2008 voters.
Republicans do not have the disadvantages they had in 2010. Then they lost competitive races in Nevada, Colorado and Delaware because of second-tier candidates. Candidate quality is distinctly better this year.
The vulnerable Republican Senate seats in Kentucky and Georgia are in increasingly better shape with Mr. McConnell running a masterfully disciplined campaign and the Georgia runoff concluding without major bloodletting.
The turf also is more favorable to the GOP than four years ago. Then 13 competitive races were in states that Barack Obama won in 2008 and four in states that John McCaincarried: The GOP picked up four seats in blue states and two in red states. This year seven competitive races are in red states won by Mitt Romney and seven in blue states Mr. Obama won, two by less than five points.
The Washington Post recently forecast the GOP has an 86% chance of taking the Senate and the New York Times earlier gave Republicans a 56% probability. Maybe. But there are 103 long days to go. The candidates who play good offense most of the time and effective defense when needed are likely to win and determine whether a Republican or Democrat is majority leader.
A version of this article appeared July 24, 2014, in the U.S. edition of The Wall Street Journal, with the headline McConnell's Campaign Lesson For The GOP and online at WSJ.com.