This chart shows why sky-high consumer confidence could be good news for Republicans in the midterms

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Pedestrians pass the U.S. Capitol.

• Of the many issues that Americans care about on election day, confidence in the economy is on the top of most voters' lists.
• And if history is any guide, that will make it harder for Democrats to regain control of the House this year, according to a CNBC analysis of past midterm results.
• Consumer confidence is currently higher than it's been in all but one midterm election since 1954. In that election, the 1998 midterm, the party in the White House gained five seats.

Sky-high consumer confidence could mean Republicans are in for some good news on Election Day.

The latest read on consumer confidence Tuesday showed that Americans are more optimistic about further growth than they have been since 2000, according to the monthly index tracked by the Conference Board.

If history is any guide, that will make it harder for Democrats to regain control of the House this year, according to a CNBC analysis of past midterm election results.

That buoyant sentiment is being propelled by a strong labor market, as the unemployment rate remains at historic lows and wage growth shows signs of perking up. President Donald Trump wasted little time in tweeting the good news.

But the good news for consumers may spell trouble for Democrats hoping to win back control of the House in next week's midterm election. The party needs a net gain of 23 seats now held by GOP incumbents.

To be sure, voter opinion polls have given Democrats reason for optimism, and political analysts say the party's chances of winning back the House are good. The consumer confidence data, though, suggest that Democratic hopes for a "blue wave" might not come to fruition.

Based on the University of Michigan's survey data, consumer confidence is higher than it's been in all but one midterm election since 1954. In that election, the 1998 midterm, the party in the White House gained five seats. Democrat Bill Clinton was president then.

On the other hand, the party in power in the White House has tended to lose House seats in midterm years when confidence levels were lower. Once of the worst routs came in 2010, when the Michigan sentiment index averaged 71.3 in the 12 months before the election. Democrats lost 63 seats that year.

In 1982, after the 12-month average confidence level fell to 67, Republicans lost 26 seats, shortly after Ronald Reagan was elected by a nearly 10-point margin.

Still, there are many other issues on voters' minds in this midterm election, including recent partisan violence, worries about the availability of affordable health care and immigration reform.

The recent slide in the stock market may be weighing on consumer confidence in ways that haven't yet shown up in the latest survey numbers. Stocks have fallen sharply in the last month and home price gains have slowed, a sign that rising interest rates may be hurting housing demand.