WASHINGTON (CNN) The Democratic Party's two best pickup opportunities in the Senate playing field are close contests in the final days of campaigning, according to new CNN Polls conducted by SSRS .

Democrat Kyrsten Sinema's lead over Republican Martha McSally in the Arizona Senate race has narrowed, from a 7-point advantage in September to a 51% to 47% split now -- a divide that is within the poll's margin of sampling error.

In mid-September, a sizable 17% of likely voters said they hadn't yet made up their minds about this critical Senate contest, that's now dropped to just 5%. As voters have shifted, McSally gained ground on Sinema among women (while Sinema's support has held roughly even at 56%, McSally has climbed from 35% to 41% among women voters) and among independents (a 49% Sinema to 39% McSally divide in September stands at 52% Sinema to 44% McSally now).

As the campaign there has turned sharply negative, both candidates have seen their unfavorability ratings rise, with the percentage saying they have an unfavorable view of each candidate climbing 11 points. Views of Sinema remain more positive than negative (49% favorable to 41% unfavorable) while voters tilt narrowly negative on McSally (44% favorable to 47% unfavorable).

In Nevada, just three points separate Democrat Jacky Rosen and incumbent Republican Dean Heller, about the same as in September. Still, 10% of likely voters in the state say they haven't yet made a firm decision on the race.

There's been almost no change in the Nevada survey in the demographic divides fueling voter preferences. There remains a sharp gender gap, with a majority of women behind Rosen and most men backing Heller. White voters with college degrees narrowly break toward Rosen, while whites without a degree favor Heller by a wide margin. Non-whites prefer Rosen by a better than 2-to-1 margin (64% to 28%).

And while Rosen's favorability rating remains slightly positive (46% have a positive view, 42% a negative one among likely voters, both positive and negative views have ticked up since September), Heller seems to have improved his marks since our last poll, from a net negative 46% unfavorable to 43% favorable read in September to a 47% favorable to 45% unfavorable mark now.

Donald Trump's approval rating has risen in both states. Likely voters in Nevada are about evenly split on the president, 49% approve of the way he's handling his job as president, 48% disapprove. That compares with a 51% disapprove to 45% approve mark in September. In Arizona, 47% of likely voters approve of Trump, 51% disapprove, an 8-point improvement on the approval side.

With Democratic campaigns across the country focusing on health care and Donald Trump focusing Republican candidates on immigration, the polls suggest voters' priorities have shifted along partisan lines in both states. Immigration now dominates on the right as the economy has faded as an issue among Republicans in both states. In Nevada, 42% of Republicans say immigration is the most important issue in their senate vote, while just 20% say it's the economy. In September, 34% chose the economy, 28% immigration. In Arizona, 50% of Republicans call immigration their top concern vs. 19% who choose the economy, those figures were 35% and 25% respectively in September.

Among Democrats, meanwhile, there is sharp consolidation around health care as the deciding factor in their Senate vote. About half of Democratic likely voters in each state now say it's their top concern (49% in Nevada and 50% in Arizona), an increase of 14 points in Nevada and 9 points in Arizona.

In both states, a majority of voters have historically cast their ballots before Election Day. In the last midterm election in 2014, 78% of Arizona votes were cast pre-election, as were 56% of Nevada ballots. In Arizona, the CNN survey finds a majority of likely voters say they have already cast their ballots, with those voters breaking toward Sinema, 54% to 43%. Voters who say they plan to cast their ballots on election day favor McSally, 59% to 39%. In Nevada, fewer voters have cast ballots thus far, about 41% of likely voters according to the poll. Among those who say they've already cast a ballot, Rosen has a narrow edge, 49% to 45%, while those who plan to vote on Election Day are about evenly split.

The race for Nevada's open governor's seat is a near-even split: 46% back the Democrat Steve Sisolak, 45% the Republican Adam Laxalt. In Arizona, incumbent Republican governor Doug Ducey leads Democrat David Garcia by a 7-point margin.

The CNN Polls in Arizona and Nevada were conducted by SSRS October 24 through 29 among random statewide samples reached on landlines or cellphones by a live interviewer. In Arizona, results for the full sample of 1,007 adults have a margin of sampling error of plus or minus 3.7 percentage points, for the subset of 702 likely voters it is plus or minus 4.4 percentage points. In Nevada, results for the full sample of 998 respondents have a margin of sampling error of plus or minus 3.8 percentage points. It is 4.8 for results among the 622 likely voters.