It was a holiday weekend, but President Donald Trump and rival Bernie Sanders didn’t exactly exchange greeting cards.

Instead, the political foes clashed via Twitter over the nation’s new tax legislation, which Trump signed into law Friday.

“Today, it was my great honor to sign the largest TAX CUTS and reform in the history of our country,” the president tweeted, soon after signing the $1.5 trillion bill.

On Saturday, Trump touted the plan as the culmination of a successful first year in the Oval Office.

“The Tax Cut/Reform Bill, including Massive Alaska Drilling and the Repeal of the highly unpopular Individual Mandate, brought it all together as to what an incredible year we had,” he tweeted.

Sanders, a U.S. senator from Vermont, prefaced his weekend tweets by posing a question Thursday.

“Doesn’t it tell us a lot about Republican priorities,” Sanders asked, “when the tax breaks for corporations are permanent, while the tax cuts for working families expire at the end of 8 years?”

Then on Saturday, Sanders poked fun at reports that Trump had told friends during a Mar-a-Lago dinner in Florida on Friday night that, “You all just got a lot richer.”

“At least Trump is finally telling the truth about his tax bill,” Sanders wrote.

That same day, however, the president reminded his Twitter followers:

“The Stock Market is setting record after record and unemployment is at a 17 year low. So many things accomplished by the Trump Administration, perhaps more than any other President in first year.”

Then Sunday, Sanders presented alternatives for what the U.S. could have done with the $1.5 trillion value of the tax legislation.

“What we could do with $1.5 trillion:

-Make college tuition-free

-Provide universal preschool

-Repair our crumbling infrastructure

-Fund CHIP for 107 years

-Rebuild Puerto Rico

What Republicans did:

-Give tax breaks to the wealthy and corporations.”

Sanders added, in a separate tweet:

“If I were the Republicans, I would worry very much about 2018,” referring to next year’s mid-term elections.

But Trump seemed unfazed by any talk of problems at the polls for the GOP. As he tweeted Saturday:

“Remember, the Republicans are 5-0 in Congressional races this year.”