Story highlights Republicans won virtually all the battlegrounds needed to keep the Senate majority

The Donald Trump wave helped several incumbents hold on to their seats

Washington (CNN) Republicans pulled off a political stunner Tuesday night -- running the table down-ballot and keeping control of the House and Senate, CNN projects.

In a year when the GOP was almost entirely on defense, the party's incumbents -- many outspent and hobbled by struggling campaigns -- managed to survive a political landscape that long appeared all but certain to cost them the Senate.

Democrats believed they had the perfect mix: Near-locks in blue Illinois and Wisconsin. Top-grade recruits in red states Indiana and Missouri to get them close. And Donald Trump would drag down Republican incumbents in the battlegrounds of Pennsylvania, New Hampshire and North Carolina.

Then, on Tuesday night, everything went wrong for them.

The biggest surprise is that Trump was no drag on the GOP ticket at all -- and might have even helped carry the party.

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