See Marco Run. Last week, Sen. Marco Rubio Marco Antonio RubioSunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Florida senators pushing to keep Daylight Savings Time during pandemic Hillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll MORE (R-Fla.) toured algae-affected waters on Florida’s Atlantic Coast. He went by helicopter and boat to see extensive algae blooms in the St. Lucie River, and talked to county officials about the issue. At a press conference, Rubio said, "This is beyond an ecological disaster. It’s an economic disaster with long-term implications." He called the algae situation "catastrophic" — even as his appearance drew criticism. As a Tampa Bay Times headline put it, "Rubio's environmental focus has critics asking, Where were you before?"

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The answer is simple: Rubio was busy nurturing his own ambition. His revived interest in being a senator is just his latest opportunistic career move. Having failed to win the GOP nomination, Rubio is once again treating Florida as a stepping stone on the path to personal gain.

Recall that Rubio's bid for the nomination was a disaster. He memorably choked in a New Hampshire debate, embarrassed himself in interactions with Donald Trump, and lost every county in his home state except one. After dropping out of the race, Rubio insisted that he would not seek a vice presidential nod or reelection to the Senate, saying "I'll be a private citizen." Rubio then repeatedly said that he would not seek reelection, tweeting in May that "I have only said like 10000 times I will be a private citizen in January."

Then last month, Rubio changed his mind and jumped back into the race. "I honestly believe that no matter who is elected president we're going to need a Senate full of people willing to act as a check and balance on the excesses of the next president," he told CNN, "and I think given the state of this race, we're going to have a lot of that over the next few years."

But these basic facts about our country’s system of checks and balances are not new. Nor did these constitutional principles stop Rubio from being disdainful about the Senate in the past. Asked by a Florida reporter to name a highlight of his first year in the Senate, for instance, he said, "I can't think of a single real high point." Defending his abysmal Senate attendance record at an Iowa town hall, Rubio said, "We're not going to fix America with senators and congressmen."

Rubio seems not to grasp that his own actions and attitude contributed to dysfunction in the Senate. Then again, to Rubio, his Senate seat was only a potential springboard to the presidency, which is why one prominent Florida paper called on him to resign in 2015.

Consider that Rubio has refused to promise that he will serve out his full term if reelected. Or that he skipped a foreign policy hearing to announce his bid for reelection. That pretty much sums up his guiding political philosophy: Marco first.

Rubio was also reportedly moved by the Orlando massacre to run for reelection. Convenient hypocrisy, considering that he has been no friend to LGBT Americans; he voted against giving LGBT people protection from discrimination in the workplace, and consistently opposed marriage equality. Despite previous mass shootings in Aurora, Colorado and Newtown, Connecticut, Rubio has reliably sided with the National Rifle Association on gun votes. Most recently, he voted against two Democratic-sponsored gun control measures designed to prevent attacks like the one at Pulse nightclub, and voted for two weaker Republican measures (all four failed).

Right now, Rubio has a huge lead over his Republican primary opponent. However, his reelection is no sure thing. Data from Public Policy Polling show that Rubio remains "very unpopular" in Florida; only 30 percent of voters approve of him, while 49 percent disapprove of the job he's doing. Another poll shows Rubio neck-and-neck with his likely Democratic opponent. Too bad Rubio can no longer count on a solid base of Latino support, given his immigration flip-flops, opposition to President Obama's executive action on immigration and his endorsement of Trump. And Rubio's promise to stand up to a President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE "if necessary" sounds like wishful thinking. During the primaries, it was Rubio who was humiliated by Trump calling him "Little Marco."

Rubio deserves to be made a private citizen again. He has been an ineffective, absentee lawmaker, and his brand of leadership is little more than poorly masked personal ambition.

Reyes is an attorney and columnist in New York City. He is also an NBCNews.com contributor.