When I looked at the battle for the United States Senate back in July, I said it’d be tough for the Democrats to retain control. But since then — and particularly since the party conventions — things have begun to look up for their candidates in a number of key races.

In Missouri, where incumbent Democrat Claire McCaskill is vulnerable, the Republicans nominated their least electable option from a close three-way primary. Congressman Todd Akin is firmly on the Tea Party wing of the GOP, and didn’t help himself with his comments about ‘legitimate rape’. It therefore looks like McCaskill may scrape her way to re-election: despite poor approval ratings, the latest Rasmussen poll found her leading Akin 49 to 44

And it’s not just fortuitous Republican primaries that have strengthened the Democrats’ hand. It seems that Barack Obama’s not the only one who got a boost from his party’s convention. In Massachusetts, where Elizabeth Warren had been running neck and neck with Republican incumbent Scott Brown, three new polls show Warren taking the lead — perhaps helped by her own impressive performance on the convention stage. New polls also show bumps for Democrats Tim Kaine in Virginia, Tammy Baldwin in Wisconsin and Joe Donnelly in Indiana. In Florida, where the Republicans had been talking up their chances of gaining the seat, Democrat Bill Nelson has pulled away and now looks safe — the latest Marist poll has him 14 points ahead of challenger Connie Mack. Similarly in Ohio, Rasmussen shows Democrat Sherrod Brown moving from a tie last month to an eight-point lead now.

The Republicans need a net gain of four seats to take control of the Senate, and while they’re very likely to gain Nebraska they’re also very likely to lose Maine. That means they’ll probably need to win the close races in Arizona, Montana, Nevada and North Dakota plus six of the seven contests mentioned above (or possibly five plus Connecticut) — and yet all seven seem to be slipping away from them. Just as Mitt Romney’s path to the White House is looking increasingly tough, so is his party’s route to a Senate majority.

Tags: democratic national convention, Democrats, GOP, Polls, Republicans, US politics, US Senate