By Kyle Trygstad, CQ Roll Call

So much for a predictable midterm cycle. The past month has left multiple possible outcomes for control of the Senate.

Republican groups are barraging Kansas with resources and advertising to save a three-term incumbent being challenged by an independent in a solidly GOP state. Democrats, lacking much hope for months of holding an open seat in South Dakota, are all of a sudden dropping $1 million in advertising there — and being matched by Republicans — in a last-second Hail Mary that could possibly save its majority.

Just three weeks remain until Election Day, yet control of the Senate remains a dogfight and more than a handful of seats could conceivably go either way. The GOP has at least ten states to find a path to six Senate seats and the majority, but — while public polling in most states appears to be moving in its direction — at this point the party has only locked up two Democrat-held seats in a favorable national climate.

Making matters more convoluted are the unknowns surrounding independent candidates Greg Orman in Kansas and Larry Pressler in South Dakota, who have yet to say which caucus they would join.

With so many variables and competitive races, plus potential and competitive runoffs in Louisiana and Georgia, the outcome of the midterm elections is anyone’s guess.

But as the votes start rolling in, there’s a chance the result will be one of the following three scenarios:

1. Republicans pull off a near sweep (Republicans 53, Democrats 47)

If you know anything about Senate races this cycle, it’s thata majority of the most competitive contests are playing out in states where President Barack Obama lost by significant margins in 2012 and remains unpopular. Months ago, it was clear this couldset upa GOP wave in the Senate.

The GOP’s near best-case scenario would start with picking up the open seats that Democrats declined to spend significant money to defend. Most likely, Reps. Shelley Moore Capito (R-WV) and Steve Daines (R-MT) would win seats held by Democrats for at least the past 30 years and head to the north end of the Capitol. From there, former South Dakota Gov. Mike Rounds must close out a late-breaking, four-candidate, open-seat race featuring millions in spending from both national campaign committees.

The party would also defeat Sens. Mark Begich (D-AK) and Mark Pryor (D-AR) in states Romney won, plus take out Sen. Mark Udall (D-CO) and pick up the open seat in Iowa. Despite their other losses, Democrats could still hold North Carolina.

Republicans would also hold in Kansas, home to the GOP’s most vulnerable incumbent, and go into potential runoffs in Louisiana and Georgia with at least a 51-seat majority and likely to increase that by two.

With the majority in hand, Republicans would be favored to defeat Sen. Mary L. Landrieu (D-LA) in a Dec. 6 runoff. And a month later, it would be a challenge for Democrats to get out the vote in the Peach State in the dawn of the new year.

Under this scenario, the GOP would be favored to hold in the overtime periods and control 53 Senate seats in the next Congress. Not only would Senate Minority Leader Mitch McConnell have survived his competitive challenge in Kentucky — something that became more likely Tuesday — the man newly elected to a sixth term would be preparing to lead a majority.

Republicans add: Montana, West Virginia, South Dakota, Alaska, Arkansas, Colorado, Iowa, Louisiana

Democrats add: nothing

2. Tied going into runoffs (Republicans 51, Democrats 49)

There is a possibility that not only will the majority not be decided on election night, but the parties will be tied once all the races are called. That would mean Republicans and Democrats would both have 49 seats going into the potential Dec. 6 runoff in Louisiana for Landrieu’s seat and the Jan. 6 runoff in Georgia for the seat of retiring GOP Sen. Saxby Chambliss.

There are multiple combinations for this scenario, and here is one: Republicans would pick up Democratic seats in Montana, West Virginia, South Dakota, Alaska, Arkansas and Iowa. But GOP Sen. Pat Roberts would lose in Kansas, giving Democrats hope that Orman would caucus with the party, and in turn a chance to keep the majority by holding Louisiana or winning Georgia.

For a 51-49 result here, the possibility of Orman caucusing with Democrats would keep the majority unknown until after the Peach State race is decided.

With Republicans poised to take the majority, the GOP would be favored to pick up the seat in Louisiana, where a barrage of advertising will be striking from both sides. Although Democrats see a path for Michelle Nunn to pick up the open seat in Georgia both in November and a potential runoff, the state’s GOP lean would favor David Perdue, giving Republicans a 51-49 edge — and 52-48 if Orman caucused with Republicans.

In the Hawkeye State, Republican state Sen. Joni Ernst’s victory would be the ultimate success story for the GOP, which had not been expected to pick up the seat earlier in the cycle. But Ernst has been the most pleasant surprise of 2014 for the GOP, and Obama’s unpopularity — coupled with Democratic Rep. Bruce Braley’s hiccups — could allow Democrats to lose the seat that retiring Sen. Tom Harkin has held since 1984.

This would also mean vulnerable first-term Democratic incumbents were able to hold on in both Colorado, where Obama won by 5 points in 2012, and North Carolina, a state the president lost by 2 points.

If so, Udall gets aided in the Rockies by the state’s mail-in voting as he faces a strong challenge from Rep. Cory Gardner (R-CO), whose recruitment by the National Republican Senatorial Committee in February marked a major turning point for the GOP’s chances. Sen. Kay Hagan (D-NC), elected on the president’s coattails in 2008, has led state Speaker Thom Tillis in public polling and has plenty of air support, but she was on the wrong end of a late $6 million surge of spending from the NRSC.

Republicans add: Montana, West Virginia, South Dakota, Alaska, Arkansas, Iowa, Louisiana

Democrats add: Kansas (maybe)

3. Democrats hold by the skin of their teeth (Democrats 50, Republicans 50)

It says something that both national party committees can head into the final days of this midterm cycle hopeful about their chances.

While some of the seats Republicans put in play will likely remain Democratic, the party’s recruitment successes and notable lack of “Todd Akin moments” — which crumbled its chances in past cycles — has allowed it multiple paths to the majority, rather than having to run the table in only red states.

And it’s perhaps even more remarkable that Democrats haven’t already written off more than two seats, especially with Obama’s disapproval at startling levels for the party. A major part of that is the DSCC’s incredibly successful fundraising, aided by the president and complemented by early advertising from the allied Senate Majority PAC, which helped incumbents in North Carolina, Arkansas and Alaska among others survive pointed attacks from GOP outside groups.

With that, Democrats can conceivably hold the Senate, and thanks to a couple third-party candidates, this is one way they could do it.

In South Dakota, home to one of Democrats’ two biggest recruitment misses, Pressler, running as an independent, pulls enough GOP votes away from Rounds to give Democrat Rick Weiland a victory with less than 40 percent of the vote.

This turns out to be the deciding seat and the only difference from the previous scenario, in which Republicans held a 51-seat majority. But it also puts majority-swinging power in the hands of Orman. By caucusing with Democrats, plus the party holding North Carolina and Colorado, they can afford to lose Montana, West Virginia, Arkansas, Alaska, Iowa and Louisiana.

After Orman gives Democrats a 50th seat, the Democratic majority relies on the tie-breaking vote of Vice President Joe Biden for the final two years of the Obama administration.

Republicans add: Montana, West Virginia, Arkansas, Alaska, Iowa, Louisiana

Democrats add: Kansas

AFP Photo/Mark Wilson