Donald Trump spoke in Pittsburgh yesterday, where he expressed great optimism about his party’s electoral prospects.

President Trump told supporters on Thursday that strong economic growth under his administration will help Republicans “win a lot of elections” later this year. […] “If we keep it up like this, we’re going to win a lot of elections,” Trump predicted, drawing massive applause from the crowd. “ ‘It’s the economy stupid,’ you ever hear that one?”

This has quickly become a standard presidential talking point: confronted with polls showing him and his party facing headwinds, Trump turns his attention to the economy. If economic conditions are strong, he assumes, the party in control will be rewarded by voters.

The truth is more complicated.

The economy, for example, is faring well right now, but conditions aren’t that good. The White House may choose to ignore this, but job growth in 2017 was the slowest since 2010. For that matter, if a healthy economy necessarily bolstered current officeholders, Trump wouldn’t have a woeful approval rating and Republicans wouldn’t be struggling in special elections.

What’s more, there’s the question of credit: a Quinnipiac poll released this week asked respondents, “Who do you believe is more responsible for the current economy?” A 49% plurality gave Barack Obama, not Donald Trump, credit.

But even if we put all of that aside, there’s still recent history to contend with.

In 2010, for example, Obama and Democrats had just turned the economy around and ended the Great Recession. Voters nevertheless delivered a wave election to Republicans, who took the House majority.

Four years later, in 2014, Americans saw the best year for U.S. job growth since the late ’90s – and that same year, the president’s party lost control of the Senate and saw their House minority shrink further

And there’s George W. Bush’s record. As regular readers may recall, heading into the 2006 midterms, the economy was in decent shape – the Great Recession didn’t start until 2007 – but the sitting Republican president was burdened by scandals, unpopular wars, a woeful response to Hurricane Katrina, and a failed gambit to privatize Social Security.

That same year, Democrats rode a wave into the congressional majority.

If Trump is counting on low unemployment and a rising star market – encouraging trends that began before he took office – to rescue the GOP, he’s setting himself up for disappointment.