During a news briefing that appeared on the calendar out of the blue Monday, Kevin Hassett, chairman of the Council on Economic Advisers, walked through a number of data points meant to demonstrate President Trump's ownership over the strong economy. Hassett relied not on the standard metrics generally offered by Trump (unemployment, GDP) but on specific bits of data related to small-business optimism and private investment.

Hassett insisted that he wasn't there to rebut former president Barack Obama's speech Friday, during which Obama noted that the numbers Trump often uses to demonstrate economic strength were trends that began during Obama's presidency. But Hassett did say that he had been asking press secretary Sarah Huckabee Sanders for time to address the issue. Suddenly, that request was granted.

Why is this important to the White House? In part, certainly, because Trump wants credit for good news. But in part — also certainly — it's because Trump believes that the strong economic numbers and the tax cuts he signed into law in December will be an asset for Republicans in this year's midterm elections.

That assumption is worth questioning.

Last week, the Wesleyan Media Project released new analysis of political ad data from the month of August. There were a number of interesting aspects to that data nationally, but none more so than the difference in focus between the parties.

More than half of ads supporting Democrats focused on health care, only a subset of which dealt with the Affordable Care Act (better known as Obamacare). Among ads for Republicans, a plurality of ads mentioned taxes, though only a tenth addressed tax reform. Only slightly fewer addressed immigration than taxes.

Immigration has been identified as one of the most important issues facing the economy over the past several months in Gallup polling. It's not clear whether that's reflecting or driving focus on the issue in Republican ads, but the two probably are moving in parallel.

Notice what's much lower on that chart, though: the economy. The economy is better; people are less likely to say it's the most important issue. We didn't even show taxes on that chart. It has polled at about 1 percent over the past several months.

Health care doesn't fare that well on that chart, either. A poll from the Kaiser Family Foundation released last week asked a variation on that question: What do voters most want candidates to talk about? Here, the numbers better match the ad spending above. Democrats most want to hear about health care. Republicans most want to hear about the economy, followed by immigration.

(Philip Bump/The Washington Post)

But notice what's at the top of both of those charts: The question of corruption in Washington or how government is functioning. That nearly a third of Democrats want to hear candidates talk about corruption suggests that there's another issue at play in November.

Trump himself.

Traditionally, views of the economy and views of the president have traveled hand in hand. The economy's doing well? The president is viewed well, too. It's not a one-to-one relationship, but it's linked. Consider former president Bill Clinton, who faced impeachment in 1998. Thanks in large part to the still-booming economy, his approval neared 70 percent.

Here we see that break. People who say the economy is in “excellent” shape overwhelmingly strongly approve of Trump, according to The Washington Post's new poll with our partners at ABC News. Those with a negative view of the economy overwhelmingly have a strongly negative view of the president. But those who say the economy is doing well are more likely to disapprove of Trump than approve. Nearly half of those who say the economy is doing well strongly disapprove of how Trump is doing.

(Philip Bump/The Washington Post)

Some of this is partisanship. Democrats may be willing to say that the economy is in good shape but still oppose Trump fervently. So what happens if we look only at independents?

Even among independents, those with a positive view of the economy are much more likely to strongly disapprove of Trump than to strongly approve of him. In fact, among independents with a positive view of the economy, about as many view Trump's job performance with approval as strong disapproval.

(Philip Bump/The Washington Post)

There's another traditional link that's held stronger than the one between the economy and the president: The fortunes of the president's party rely on how the president himself is perceived. If we look at the generic ballot question — whom poll respondents plan to vote for in November, the Democrat or the Republican — we see that more than half of those who say the economy is in good shape plan to vote for Democrats in the midterms.

Some of this is because Democrats and Trump opponents are still largely willing to accept Obama's view: that the good economic news is mostly a credit to Trump's predecessor. (In June, about 4 in 10 Americans said the economy was a function of Obama instead of Trump.)

But that gets at another point. Were Trump more popular, it's possible that he might be given more credit for the health of the economy than he is now. If you fervently oppose Trump's position on, say, immigration, you're probably less likely to say that Trump is doing well on the main metric on which he wants to be evaluated.

Trump's not going to get significantly more popular with Democrats or independents before the election. (His approval numbers overall have remained much flatter than his predecessors during his first year and a half in office.) Given the links above, it's hard to see how the good economy bolsters his party much if Trump's popularity remains about where it is.

Particularly because, as CNBC's John Harwood noted last week, the effects of Trump's policies have not been felt by many Americans. In March a majority of Americans said they hadn't noticed an increase in their take-home pay from Trump's tax cuts. (Most Republicans said they had.) The effect of the cuts on jobs and wages is hard to detect, which is probably why Hassett focused on other data Monday.

Another bit of news Monday: House Republicans have a plan to help bolster their chances in November. Their aim, according to Reuters? New tax cut legislation.

Whether those on the front lines of the fight for control of Congress work that into their ads remains to be seen. Last month, only 1 in 10 ads for Republicans mentioned tax reform at all.