With seven months until the midterm election, there's little for Democrats to cheer in the growing number of polls on this year's Senate contests.
Republicans have double-digit leads in the three races in red states Mitt Romney carried where the incumbent Democrat retired. West Virginia Rep. Shelley Moore Capito is up by 14 points, 49%-35%, over Secretary of State Natalie Tennant in a Feb. 20 Rasmussen poll. Former South Dakota Gov. Mike Rounds leads Democratic congressional staffer Rick Weiland 51%-31% in a Feb. 26 Rasmussen survey. Montana Rep. Steve Daines is 14 points ahead of interim Sen. John Walsh, 51%-37% in a March 18 Rasmussen matchup. These public polls mirror private ones, suggesting Republicans are positioned to win if they keep the pressure on.
The next benchmark for these races is the April 15 Federal Election Commission fundraising reports for the first quarter. All three Republican candidates had a commanding financial advantage at the end of 2013. If they maintain the money edge for 2014's first and second quarters, Democratic donors may start cutting their losses and shifting funds elsewhere.
Then there are the four red states where incumbent Democratic senators are trying to retain their seats. Each race is a dogfight, though every Democrat has much higher name identification than the Republican challenger.
Take Alaska: 91% of Alaskans felt they knew enough about Democratic Sen. Mark Begich to have an opinion of him in a Jan. 22 Harper poll for American Crossroads (the super-PAC I helped organize). The Republican front-runner, former Natural Resources Commissioner Dan Sullivan, had 73% name recognition. Yet a March 24 Rasmussen survey found the race tied at 44%, similar to the earlier Harper poll matchup. Mr. Sullivan's name recognition is probably overstated: Some voters probably confuse him with Anchorage's two-term mayor, also named Dan Sullivan.
In a Feb. 20 poll from Democratic firm Hickman Analytics, Arkansas's Democratic Sen. Mark Pryor had 94% "effective recognition" to Rep. Tom Cotton's 79%. Yet Mr. Pryor only led Mr. Cotton by 40%-37%.
Another Hickman poll on Feb. 20 showed Louisiana Democratic Sen. Mary Landrieu with 95% "effective recognition," while her leading GOP opponent, Rep. Bill Cassidy, clocked in at 42%. Despite this substantial gap, Mr. Cassidy led Ms. Landrieu by four points (46%-42%).
In a third Feb. 20 Hickman poll, North Carolina Democratic Sen. Kay Hagan had a 50-point "effective recognition" advantage over the leading Republican, State House Speaker Thom Tillis (84% vs. 34%). Mr. Tillis only trailed by four points.
There is a similar pattern in blue states President Obama won in 2012. The Democratic opinion research firm Public Policy Polling showed incumbent Colorado Sen. Mark Udall narrowly ahead of Rep. Cory Gardner, 42%-40%, in a March 16 poll. Yet Mr. Gardner has been in the race only five weeks and has significantly less name recognition than Mr. Udall, having represented one-seventh of Colorado's citizens for two terms in the House.
An incumbent with much higher name recognition than an opponent—but only a narrow lead this early on—is evidence of a low ceiling of support. It also suggests that the challenger can rise as his background, values and agenda becomes better known.
Democrats understand this, which is why Sen. Harry Reid's Majority PAC, liberal interest groups, and some Democratic candidates have launched early attacks on Republican challengers, attacking Mr. Sullivan as a carpetbagger and Messrs. Cassidy, Cotton and Tillis as shills for the insurance industry. They want to define the GOP candidates before they define themselves—like the Obama campaign did to Mitt Romney in 2012.
It won't be easy for Republicans to offer the right mix of messages and raise the funds to deliver those messages. They must keep their fire trained on the economy, ObamaCare's shortcomings, the national debt and the military's hollowing-out. They must convince voters that Democratic incumbents have blindly followed Mr. Obama. And they need to sharpen awareness of their own histories and values. The last is often given short shrift.
Right now, the Senate midterms feature crucial races between well-known, well-defined Democrat incumbents and lesser-known, largely undefined Republicans. The political map and landscape favors the GOP. But dislodging a sitting U.S. senator is hard—and Republican hopes of taking the Senate depends on doing exactly that. Republicans should be encouraged but not complacent. Mr. Reid and his allies will make certain these races get very intense and very ugly soon.
A version of this article appeared April 3, 2014, in the U.S. edition of The Wall Street Journal, with the headline Why The Senate Races Will Soon Get Ugly and online at WSJ.com.