The one thing President Trump has had, through thick and thin, is his base. And amid signs that it was beginning to waver, Trump assured us Monday that it was “stronger than ever.”

Then came more polls that drive home how untrue that is.

A CNN poll and an Investor's Business Daily poll, both released late Monday, show somewhat different pictures of Trump's overall approval. The CNN poll pegs it at 38 percent — around where it has been in other polling for a while — while the IBD poll shows it at a painfully low 32 percent. That's the lowest of any high-quality poll in Trump's entire presidency.

But both polls actually reinforce the idea that Trump's support among the base is in decline.

The IBD poll shows Trump's decline even more acutely, with 71 percent of Republicans approving of him. That's down from 83 percent just a month ago.

The CNN poll shows it in a more nuanced way. While 83 percent of Republicans in that poll still approve of Trump, the number who strongly approve of him has declined from 73 percent in February to 59 percent today.

These polls come on the heels of a Quinnipiac University poll last week that also showed Trump's strong approval among Republicans dropping off. In that poll, just 53 percent of Republicans strongly approved of the president — down from a previous low of 62 percent.

Another common thread running through these polls is Trump's decline among the working-class voters who were so key to his win in the 2016 election. The Q poll last week showed them disapproving of Trump more than they approved of him for the first time. The IBD poll shows Trump's biggest decline coming among those making between $30,000 and $50,000 per year; 40 percent of this group approved of Trump last month, but it's down to 27 percent today. Another of the biggest declines was among high school-educated voters, among whom Trump's approval dropped by 11 points. The CNN poll shows Trump's strong approval among whites without college degrees declining from 47 percent in February to 35 percent today. This is a group among which Trump beat Hillary Clinton more than 2-to-1.

But the most crucial numbers remain the approval ratings among Republicans. The president maintains sway over congressional Republicans as long as GOP base voters remain firmly in his camp. And holding that base has been Trump's entire political strategy, with almost everything he does alienating 60-65 percent of country but aiming to rally the base — against the media, against the establishment and often against long-established political norms. The president does something controversial, the media jumps on it, Trump screams “fake news,” and the base rallies.

That strategy is increasingly starting to come into question. The 71 percent of Republicans who approve of Trump in the IBD poll is actually lower than the lowest that President Barack Obama's approval was ever measured among Democrats in a high-quality poll. Obama fell into the mid-70s in high-quality polls, but never lower, according to RealClearPolitics.

In other words, it may be time to stop talking about how Trump's base strategy is keeping him viable in Washington. And it may be time for a new strategy for the president.

Correction: This post initially said Trump's approval had dropped by 12 points in the CNN poll among those without college degrees. The decline was actually among *whites* without college degrees.

Update: Trump labeled the polls "Fake News Suppression Polls" in a tweet Tuesday afternoon.