The Dow Jones industrial average will reach 24,000 by the end of this year if President Donald Trump and the Republicans who control the House and Senate deliver on corporate tax reform, Wharton School finance professor Jeremy Siegel told CNBC on Thursday.
"I would love to see personal tax reform and lower those personal rates but what I think what is more probable and what I think Congress should attack first is corporate tax reform," Siegel said on "Squawk Box," a day after the Dow closed above 22,000 for the first time ever.
The longtime stock bull predicted on CNBC in February that Dow 22,000 was "on the horizon." The index was trading around 20,504 at the time.
"The market is going up on the Republican agenda. It's not going up on the Trump agenda," Siegel said Thursday. "The only thing about Trump is he's not going to veto the legislation that Congress has. And that's a positive."
Siegel said the "fiasco" with the Senate Republicans' health-care bill makes Congress more determined to get something done with tax reform.
"What they thought is that they're going to get a trillion dollars from the health-care reform. Of course that was pie in the sky," he said.
The White House and some conservative groups are targeting red-state Democrats in hopes of winning support for a tax overhaul, and Senate Democrats have offered to work with Republicans on a bipartisan package.
Trump, along with Republicans in the Senate and House, has called for major tax cuts for businesses and individuals, saying that lower tax rates would drive the economy and grow jobs.
On the fundamentals, Siegel said the Dow could get "another thousand" out of strong earnings alone. "What the stock market cares about is interest rates and earnings. And both of them are doing well."
While the Federal Reserve has raised rates twice this year — with about 50-50 odds of another hike in December — the cost of borrowing money remains at historic lows, which aids the economy and the stock market.
The lower dollar is also helping to drive equities higher, Siegel said. The dollar index against a basket of major currencies rose about 5 percent after the election to mid-December. But since then, it's fallen about 9 percent.
The Dow has gained more than 20 percent since the election as of Wednesday's close; the S&P has risen over 15 percent; and the Nasdaq has climbed more than 22 percent.