A pair of Senate recruits have given Democrats a new lease on life in Arizona and North Dakota, while the GOP is newly optimistic about victory in the Florida Senate contest thanks to its own new recruit.

But in all three cases, the jury is very much out on these new candidates for the 2012 Senate battle.

Rep. Connie Mack (R-Fla.) on the night of his 2004 House primary victory — the last tough campaign he has run. Republicans are hoping Mack turns out to be a top-tier Senate candidate.(AP Photo/The News-Press, Daniel Barry, File)

The trio are being counted on to as game-changers their respective races. But neither Heitkamp, Carmona nor Mack are known quantities as campaigners.

Mack hasn’t had a tough race since his first House primary in 2004. Heitkamp hasn’t been on the ballot since her 2000 gubernatorial loss, and Carmona has never run for political office before.

In the case of Mack, a new Quinnipiac poll shows him trailing Nelson just 42 percent to 40 percent. But it’s also quite possible that his numbers are inflated because he shares a name with his father, a former senator in his own right. (Of course, that can also help on Election Day.)

There are two big questions for Mack: money and immigration. He raised a strong $1.9 million for his 2004 House win but didn’t even collect $1 million for his 2010 re-election bid. And he could also have significant problems in the primary, given his stance on illegal immigration.

Heitkamp was something of a rising star in North Dakota politics in the 1990s and was in a tight race for governor until she was diagnosed with breast cancer just weeks before the 2000 election. She won more than 60 percent of the vote in three campaigns as tax commissioner and attorney general, but fell to now-Sen. John Hoeven (R), 55 percent to 45 percent in the governor’s race.

It’s now been 12 years since that loss, and campaigns today are quite different than they were then. Republicans have already said that Heitkamp has been supportive of President Obama and spoke out in favor of his health-care bill, both which could hurt big time in North Dakota. The good news is that Democratic polling shows Rep. Rick Berg (R-N.D.) is hardly untouchable.

Carmona is even more of an x-factor than the first two. Appointed surgeon general by George W. Bush in 2002, he served until 2006, after which he became critical of the administration’s relationship with the scientific community.

Republicans tried to recruit him to run against Gov. Janet Napolitano (D) in 2006, so even they have to acknowledge he’s got some appeal. At the same time, Napolitano was so popular then that many top names had already passed on the race, and the GOP needed a warm body.

Carmona will have to prove that he can raise money and survive the vetting process; his confirmation process in 2002 was difficult and his personal background — which includes shooting a mentally-ill man and an often-rocky employment history — wasn’t exactly an asset.

Democrats have already seen one candidate they praised — former Gen. Ricardo Sanchez in Texas — struggle to get any kind of footing thanks to those same problems. In fact, even aside from being another Hispanic Senate candidate running in the Southwest, a lot about Carmona’s profile sounds like Sanchez — including their non-traditional political backgrounds, ties to Republicans and colorful pasts.

The goal for Carmona and the others is to avoid a similar fate.

The bar is somewhat lower for Heitkamp and Carmona, because they are running in open seat races and come from smaller states, but even they will start out as underdogs.

Neither Arizona nor Florida made the line this month, but North Dakota’s stranglehold on the No. 1 spot is suddenly more in doubt.

To the line!

10. New Mexico (Democratic-controlled): This race has yet to really heat up, but right now it’s not looking good for state Auditor Hector Balderas in the Democratic primary. Rep. Martin Heinrich (D) has been solidifying support and has twice as much cash-on-hand.

The young Balderas will have to raise his profile nationally if he wants to compete. On the GOP side, Rep. Heather Wilson (R) still dominates in fundraising, although tea party candidate Greg Sowards’ campaign collapse will make it easier for Lt. Gov. John Sanchez to solidify tea party support. That could force the moderate Wilson to run further to the right, complicating the general election in this blue-leaning state. (Previous ranking: 9)

9. Wisconsin (D): Yes, Republicans have a crowded primary between state Sen. Jeff Fitzgerald, former governor Tommy Thompson and ex-Rep. Mark Neumann. And, yes, that primary will almost certainly turn into an ideological battle between the tea party and establishment wings of the GOP.

And yet, the fact that Democrats seem set on nominating Rep. Tammy Baldwin, among the most liberal House members, keeps this race on the line and competitive. Democrats insist Baldwin will win by casting herself as a populist fighter, but Republicans will do everything they can to portray her as a Madison liberal out of step with the rest of the state.

Also worth noting: Neumann won the backing of Sens. Rand Paul (R-Ky.) and Tom Coburn (R-Okla.) this week. (Previous ranking: 10)

8. Ohio (D): The primary field cleared for GOP state Treasurer Josh Mandel since our last line, with former state senator Kevin Coughlin dropping out of the race. That’s the good news for the GOP.

The bad news is that Sen. Sherrod Brown (D) continues to look pretty solid, and even Republicans acknowledge the task ahead of them is formidable. We have yet to see much from Mandel’s campaign beyond its fundraising prowess, but along with the candidates mentioned above, his mettle will matter greatly in making this race competitive. (Previous ranking: 8)

7. Virginia (D): What did the 2011 legislative elections in the Commonwealth tell us about the Senate race between former governors Tim Kaine (D) and George Allen (R)? That it’s going to be very, very close. That the Virginia state Senate tipped to Republicans by just 225 votes in a single district tells you everything you need to know about the competitiveness of Virginia going forward.

This has been, and will continue to be, the marquee toss-up Senate race of the 2012 cycle. With the possible exception of... (Previous ranking: 5)

6. Massachusetts (Republican-controlled): The battle lines are already being drawn in Massachusetts -- just look at Crossroads GPS’s new ad and Democrats’ response. Republicans will attack Harvard Law Professor Elizabeth Warren as a socialist allied to a radical, violent movement (Occupy Wall Street).

Democrats will use those attacks to stir up liberal outrage on Warren’s behalf while painting Sen. Scott Brown (R) as a GOP puppet. This race is already all but tied in polls, so expect the attacks to only get nastier. (Previous ranking: 6)

5. Montana (D): Rep. Denny Rehberg’s (R) campaign has now dropped its lawsuit against the city of Billings over its response to a wildfire on his property in 2008, saying that the process has become too much of a political hot potato.

Democrats believe that if they can make this race about the two candidates — Rehberg and Sen. Jon Tester (D) — rather than a referendum on the president, they can win this race. Rehberg’s move seems to suggest he would rather not have his lawsuit distract from the an electoral environment that should favor his party in conservative Montana. (Previous ranking: 7)

4. Nevada (R): Sen. Dean Heller (R) said recently that he knew keeping his Senate seat “is not going to be easy,” and he was right.

After a couple good months, he’s stumbled by cancelling a meeting with the Latin Chamber of Commerce, and Democrats quickly capitalized on the gaffe with ads. But unless it becomes part of a pattern, the dynamics of this race haven’t changed much. Heller’s real concern is catching up to Rep. Shelley Berkley (D) in fundraising. (Previous ranking: 4)

3. Missouri (D): Want to know why Missouri Republicans don’t have much faith in their candidates here? Look no further than the handling this week by Rep. Todd Akin’s (R) campaign of an “endorsement” from House Budget Committee Chairman Paul Ryan (R-Wis.). Akin’s campaign proudly touted the endorsement on Wednesday. The only problem was, Ryan wasn’t endorsing Akin’s campaign.

Ryan’s people said later that he had merely endorsed Akin’s work on the Budget Committee, and Akin’s campaign was forced to acknowledge its over-zealousness. This kind of thing quite simply doesn’t happen on top-flight campaigns.

Republicans are hoping beyond hope that businessman John Brunner can run a more credible campaign, because Sen. Claire McCaskill (D-Mo.) is pretty vulnerable. (Previous ranking: 3)

2. Nebraska (D): Democrats here are really rolling the dice when it comes to Sen. Ben Nelson (D). Recognizing that he is perhaps their only chance of holding this seat, they have spent $1.25 million running, ahem, “issue” ads on his behalf during the off-year. The ads are being aired by the state party, but the Democratic Senatorial Campaign Committee has transferred money to cover most of the bills.

Nelson, for his part, doesn’t sound overly enthused about running again, and claims he hasn’t made up his mind, but national Democrats are cautiously optimistic. If Nelson retires, this probably vaults over North Dakota to become the most likely seat to flip parties, particularly given new developments in that state (see below). (Previous ranking: 2)

1. North Dakota (D): Democrats insist that Rep. Rick Berg (R) is vulnerable — and they even have a poll to make the case!

Heitkamp’s candidacy gives the party a credible nominee, but this is still North Dakota in a presidential year. We’re willing to hold open the possibility that this race is competitive, but it still seems like very much of a long shot at the moment. (Previous ranking: 1)

Chris Cillizza and Rachel Weiner contributed to this report.