By Stuart Rothenberg, CQ Roll Call

WASHINGTON — A few weeks ago I wrote Senate Republicans would gain at least seven seats, even though the Rothenberg Political Report/Roll Call race ratings showed a likely Republican gain of five to eight seats.

That expectation was based on national survey results showing the president extremely unpopular and voters unhappy with the direction of the country, as well as state polling that showed Democratic incumbents well below the critical 50 percent threshold in ballot tests against their GOP opponents.

My admission shouldn’t have been all that startling. After all, Mitt Romney carried seven states where Democrats are defending Senate seats, and in this era of declining ticket-splitting, it wouldn’t be surprising for anti-Obama voters to vote against the Senate nominees of the president’s party.

Indeed, midterm electoral history would suggest Democrats have an uphill battle to hold onto the Senate.

But, as I pointed out in the column, with only three Democratic Senate seats in the bag for GOP — South Dakota, West Virginia and Montana — Republicans can’t yet be certain they will net the six Senate seats they need for a majority in the next Congress.

So what could/would cause me to change my expectations over the next month? How could Democrats alter the election’s trajectory?

First, Democrats still may be able to localize elections in a few states — the most likely prospects are North Carolina and Alaska, which were carried by Romney, and two swing states won by President Barack Obama, Iowa and Colorado. Doing so would inoculate the Democratic nominees (three incumbents and one open seat hopeful) from Obama’s near-toxic political standing.

Democrats certainly have lowered the boom on North Carolina’s Thom Tillis, Alaska’s Dan Sullivan, Iowa’s Joni Ernst and Colorado’s Cory Gardner, and it isn’t unreasonable to believe that they can hold all four seats by discrediting the GOP nominees.

But, as I previously noted, plenty of Republicans who lost in 2006 and Democrats who lost in 2010 tried that strategy — unsuccessfully. So while it isn’t impossible to localize a race, the broad national mood and the states in play combine to make that a tough task. And the president’s recent assertion that while he isn’t on the ballot next month his policies are only makes localizing more difficult for Democrats.

Second, Democrats may be able to register and turn out additional voters, who could change the arithmetic of the election.

I have been assuming a 2014 electorate that looks more like the last midterm electorate than either of the past two presidential electorates. The 2010 electorate was much older and whiter than the 2008 and 2012 electorates, and there is no reason to believe that Democrats won’t suffer again from this year’s midterm electorate.

But Democrats are making an effort to register African-American voters in a number of states, mobilize Democratic voters in Alaska’s remote villages, and turn out both younger voters and reliable Democratic voters who in the past sat out midterm elections. If they can change the electorate, they can change their chances of holding on to a handful of states that I am expecting them to lose.

As I wrote in mid-April, it’s hard to quantify the effectiveness of the Democrats’ ground game, but that doesn’t mean it can’t have a significant impact in November. Still, given the president’s problems and signs of lower Democratic enthusiasm, it’s difficult to imagine widespread sufficient Democratic turnout gains.

Third, the Democrats’ money advantage could help limit GOP gains to five seats or fewer, keeping the Senate in Democratic hands for the president’s final two years.

“We have been waiting for our big donors to come into (competitive) races, but I’m starting to think that they aren’t going to come,” said one worried Republican consultant to me recently.

The veteran insider fears the party’s hype about winning the Senate in 2010 and 2012 had turned major GOP donors into skeptics about 2014 as well.

Campaigns and outside groups generally seem to be awash in money these days, but some GOP insiders are particularly worried about Democratic spending in North Carolina making it easier for Democrats to squeeze out a narrow victory.

Finally, news is always a wild card. Some event could raise questions about the Republican Party, change the election’s narrative or cause the country, or at least Democrats, to rally around the president. The beheadings by ISIS and the president’s decision to bomb the group’s forces in Iraq and Syria may help Obama’s numbers inch up, but any electoral impact would likely be negligible.

Obviously, a significant improvement in the president’s job approval ratings could change the national dynamic and improve the chances of a few endangered Democratic senators and Senate candidates.

Every election involves some tension between national and state forces. National factors look quite strong to me now, but that doesn’t mean that I couldn’t have a different view in three weeks.

At this point, however, with Election Day fast approaching, I remain where I was a month ago. I still don’t like where many Democratic Senate nominees are now positioned.

Photo: Diliff via Wikimedia Commons

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