Dems can hold Senate

The early 2012 conventional wisdom was that Republicans would easily take control of the Senate this November. It was a perfectly reasonable supposition — 23 Democratic seats are up for reelection, with the GOP defending just 10. Given that Republicans need a net pickup of only four seats for an outright majority, the numbers appeared to be squarely in their favor.  

But elections have a funny way of confounding even the surest predictions, and it’s increasingly evident that Mitch McConnellAddison (Mitch) Mitchell McConnellSessions: 'We should be like Canada' in how we take in immigrants NSA spying program overcomes key Senate hurdle Overnight Finance: Lawmakers see shutdown odds rising | Trump calls for looser rules for bank loans | Consumer bureau moves to revise payday lending rule | Trump warns China on trade deficit MORE might want to hold off on ordering those new business cards.

Six of the seats where Democrats are playing defense are in red states, and one of them is Missouri Sen. Claire McCaskillClaire Conner McCaskillNSA spying program overcomes key Senate hurdle Senate campaign fundraising reports roll in Dems search for winning playbook MORE’s. McCaskill remains the most endangered Democratic incumbent, her hopes resting on a nasty GOP primary that might produce a weakened opponent. And in Nebraska, Democratic former Senator and Gov. Bob Kerrey trails badly, although he’s making Republicans spend money in a state they had chalked up in the win column just a few months ago.

But in North Dakota, where Republicans thought they had an easy pickup when Sen. Kent Conrad retired, former Attorney General Heidi HeitkampMary (Heidi) Kathryn HeitkampPawlenty opts out of Senate run in Minnesota GOP's Cramer won't run for ND Senate seat GOP Rep. Cramer 'trending' toward ND Senate run MORE leads in the early polling. And West Virginia’s Joe ManchinJoseph (Joe) ManchinMcConnell to Dems: Don't hold government 'hostage' over DACA Lawmakers see shutdown’s odds rising Senate campaign fundraising reports roll in MORE is headed toward an easy reelection after narrowly winning the seat in a 2010 special election. 

The final two Democratic seats in red states, Montana and Virginia, are both neck and neck — same as they were in 2006, when their outcome decided control of the Senate. We could see a repeat this November. 

Republicans have targeted open Democratic seats in New Mexico and Wisconsin, both fiercely competitive. However, Wisconsin will be far less competitive if Republican primary voters reject their best candidate, moderate former Gov. Tommy Thompson. 

Beyond that, Republican challenges to Democratic incumbents in Florida, Michigan, Ohio and Pennsylvania all appear to be fizzling. Florida Republicans have failed to recruit a top-tier challenger to Sen. Bill NelsonClarence (Bill) William NelsonSenate campaign fundraising reports roll in Week ahead: Tech giants to testify on extremist content Puerto Rico's children need recovery funds MORE, who has commanding leads in polling. Ditto with Pennsylvania. In Michigan, former GOP Rep. Pete Hoekstra cratered after airing a racist attack ad during the Super Bowl, and never recovered in his bid to unseat Sen. Debbie StabenowDeborah (Debbie) Ann StabenowSenate Finance Dems want more transparency on trade from Trump Prominent Michigan Republican drops out of Senate primary GOP chairman shoots down Democrat effort to delay tax work until Jones is seated MORE. And in Ohio, no non-presidential candidate has faced more negative super-PAC money than Sen. Sherrod BrownSherrod Campbell BrownSenate campaign fundraising reports roll in Commerce sends Trump long-awaited steel report GOP Rep. Jim Renacci announces Ohio Senate bid MORE, yet he has weathered at least $5 million in attacks with limited erosion in support. 

As of today, that means the GOP is favored in two states and faces toss-up battles in perhaps five more. Remember, they only need four of those to win control, but that’s assuming they don’t lose any seats.

And make no mistake — the Democrats are also playing offense. 

There’s a real fight in Massachusetts, where Republican fluke Sen. Scott Brown is facing grassroots superstar Elizabeth WarrenElizabeth Ann WarrenWarren: Trump is a 'racist bully' Poll: Oprah would outperform Warren, Harris against Trump in California Democrats continue to dismiss positive impacts of tax reform MORE. In Maine, left-leaning independent and former Gov. Angus KingAngus Stanley KingMcConnell to Dems: Don't hold government 'hostage' over DACA Overnight Regulation: Regulators kill Perry plan to help coal, nuke plants | Senate Dems to force net neutrality vote | Maine senators oppose offshore drilling plan | SEC halts trading in digital currency firm Maine senators oppose Trump's offshore drilling plans MORE is likely to capitalize on Republican Sen. Olympia Snowe’s retirement.

Democrats are also competitive in Nevada and Arizona, where changing demographics are transforming the political landscape. 

And then there’s Indiana, which really should be safely Republican. Yet conservatives gifted Democrats with an opening by ousting longtime incumbent Dick Lugar in the GOP primary. Democratic nominee Joe DonnellyJoseph (Joe) Simon DonnellyDems search for winning playbook GOP anxious with Trump on trade Blue wave of 2018 stops in Indiana and Missouri MORE, a sacrificial lamb against Lugar, is even money against conservative darling Richard Mourdock. 

With Democrats in good position to take two Republican seats, and competitive in three more, it’s clear that the GOP’s path to the Senate majority is a whole lot more treacherous than it seemed a few short months ago.

Moulitsas is the publisher and founder of Daily Kos (