WASHINGTON – The pressure campaign has begun.

A conservative advocacy group called One Nation said Thursday it will run a digital ad calling on Sen. Bill Nelson to "say no to the left" and support President Donald Trump's pick for the Supreme Court, whomever that might be.

"This is merely the first step in our full-fledged advocacy campaign for the nomination and confirmation of a constitutional conservative to the U.S. Supreme Court," said One Nation president Steven Law.

Nelson said Wednesday, when Justice Anthony Kennedy announced he will retire, that a vote on a replacement should wait until after the elections, which will decide control of the Senate. But Nelson is locked in a tight race with Gov. Rick Scott and Trump narrowly won Florida.

Critics have noted that Nelson voted to confirm Elena Kagan three months before the 2010 midterms. Nelson also called for a vote on the vacancy President Obama faced in his last year, though Republicans held it up — a strategy that paid off huge with President Trump's victory.

Liberals meanwhile will insist Nelson join any fight to delay a vote.

One Nation said $10,000 is behind the Florida ad, which will run through July 3. The group stressed it's only the beginning of a "considerable advocacy campaign."

It does not disclose its donors.