"Those Senate races ultimately will decide majority control of the Senate," he said. "This is where the battle for control of Congress will be won or lost, and this is where credit unions can shine."

Senate control is a toss-up, NAFCU Political Affairs Director Dan O'Brien said.

Democratic nominee Hillary Clinton has built a substantial lead over her Republican opponent, Donald Trump. And the question is: If Clinton's lead holds up, will she also sweep Democrats into majorities in the House or Senate?

"Is this going to be a wave election?" asked CUNA chief political officer Richard Gose. A wave election refers to major gains made by one political party.

He said it remains unclear how non-traditional Republican voters who support Trump will vote in congressional races or if they will even turn out to vote. "It's difficult to predict whether traditional Republicans who don't like Trump will turn out to vote at all," he said.

Those are unchartered waters, CUNA Vice President of Political Affairs Trey Hawkins said.

"There will be new members on Capitol Hill regardless of which party controls Capitol Hill. And credit unions should be taking advantage of that opportunity," O'Brien said.

Both trade group Political Action Committees have been active this cycle. Neither contributes to presidential candidates, but both are active in congressional races.

"Any successful political action program looks at competitive races as a gift, because it gives us a chance to make a difference on behalf of a credit union friend," McKechnie said.

By the end of September, CULAC, CUNA's political committee, had contributed $2,889,000 to candidates. In addition, the committee had spent almost $600,000 on independent expenditures on behalf of congressional candidates. By the end of the current election cycle, CULAC is likely to have spent about $6 million on the election, Hawkins said.

CULAC is the fifth largest PAC in the nation, according to figures compiled by the Center for Responsive Politics.

NAFCU also operates a PAC. By the end of August, it had spent $326,500 in contributions.

The following are several of the key House and Senate races being watched by credit union political officials:

Alabama Senate: Having won his primary election, Senate Banking Committee Chairman Richard Shelby is only facing token Democratic opposition from disability-rights advocate Ron Crumpton. While he is likely to win re-election to the Senate, Shelby won't be returning as chairman of the Banking Committee, since he is term-limited from serving another term at the helm of the committee.

Idaho Senate: Republican Sen. Mike Crapo is heavily favored to win re-election in his race against attorney Democrat Jerry Sturgill. Credit union interest in this race is partially based on the assumption that if Republicans control the Senate, Crapo is in line to chair the Banking Committee.

Ohio Senate: Considered a potentially competitive race, Republican Sen. Rob Portman is opposing former Democratic Gov. Ted Strickland in this state, which is one of the battleground states in the presidential election. O'Brien said this Senate race may well help decide whether Republicans continue to control the Senate. Portman, a former director of the Office of Management and Budget, is one of the main co-sponsors of legislation that would require federal agencies to perform a cost-benefit analysis of proposed rules.

Pennsylvania Senate: The Pennsylvania Senate race between incumbent Republican Pat Toomey and Kathleen McGinty, a former secretary of the Pennsylvania Department of Environmental Protection, is rated a toss-up by many election observers. Pennsylvania is also a key battleground state in the presidential election. Toomey has been an advocate for regulatory relief for credit unions and has pushed a plan to raise the threshold for CFPB examinations from $10 billion from $50 billion.

North Carolina Senate: Republicans didn't expect the race between incumbent Republican Richard Burr and Democratic former state Rep. Deborah Ross to be competitive, Goss said. However, incumbent Gov. Pat McCrory, a Republican, is facing stiff competition from Attorney General Roy Cooper, a Democrat. McCrory pushed the controversial state transgender bathroom law that led to the state losing a great deal of business.

California House, 7th District: Incumbent Rep. Ami Bera, a Democrat, is facing Sacramento County Sheriff Rick Scott in a contest that is considered to be competitive. CULAC has made this race one of its priorities and has spent about $197,000 on independent expenditures in support of Bera's re-election effort. Bera is a former credit union board member.

Maine House, 2nd District: Incumbent Republican Rep. Bruce Poliquin, a member of the House Financial Services Committee, is facing former State Rep. Emily Ann Cain in this rematch. The last contest saw Poliquin narrowly defeating Cain. During his time on Capitol Hill, Poliquin has pushed for loosening regulations on smaller financial institutions and was a co-sponsor of the regulatory overhaul legislation pushed by Financial Services Chairman Jeb Hensarling.

Nebraska House, 2nd District: CULAC has spent $250,000 on the reelection effort of Democratic Rep. Brad Ashford in this highly competitive district. Two years ago, Ashford defeated Republican Rep. Lee Terry, one of only two Democrats who unseated Republicans. This year, he is facing Don Bacon, a retired United States Air Force Brigadier General. Democratic and Republican congressional campaign committees have placed a high priority on this seat. Hawkins described Ashford as a "solid supporter of credit unions."

New Hampshire House, 1st District: This race is considered to be close, with incumbent Republican Rep. Frank Guinta running for re-election against former Rep. Carol Shea-Porter. Guinta is a member of the House Financial Services Committee and has introduced legislation that would require the NCUA to extend the exam cycle for certain credit unions. Guinta has acknowledged receiving campaign contributions from his parents that exceeded contribution limits — leading several GOP officials in the state to call for his resignation.

New York House, 22nd District: Republican Rep. Richard Hanna decided to retire this year, setting up a competitive race between Democrat Kim Myers and Republican Claudia Tenney. CULAC has made the race a priority, spending almost $160,000 independently on the contest.