In a preview of Thursday's debate, Sen. Marco Rubio went after Donald Trump during a rally in Houston Wednesday night as he looks to jump into first place in states voting on Super Tuesday.

During his address to supporters in Houston, Rubio hit Trump for past statements on Obamacare, foreign policy and Israel, one day after the real estate mogul won his third straight early primary state. They also come merely hours after Rubio pushed back against questions on why he hasn't challenged Trump more on the issues now that he is the clear-cut favorite for the GOP nod after his third straight win Tuesday in Nevada.

"When I am president of the United States, we are going to repeal and replace Obamacare once and for all," Rubio said in his often-used stump line before turning to Trump. "The front-runner in this race, Donald Trump, has actually alluded to the fact that he thinks parts of Obamacare are pretty good."

Rubio's new line of attack came less than a week after Trump indicated his support for the Obamacare mandate during a town hall with CNN's Anderson Cooper, saying further that he doesn't want "people dying in the streets."

The Florida senator almost immediately turned to hit Trump, though not by name, for not having the know-how on day one of a potential Trump administration to deal with the Middle East. Going further, he told the crowd that he it's not enough simply to put good people in charge.

"What is the one thing the federal government has to do? It has to keep us safe. That is the job of the federal government. That is it's number one obligation and being president — your most important job is to be the commander and chief of the United States," Rubio said. "We cannot have a commander in chief that is not ready the first day in office, because Vladimir Putin is not going to wait for the next president to catch up. ISIS is not going to slow down ... there is no honeymoon period in foreign policy."

"You can't just say the way some people in this race have said — you'll probably know what I'm talking about in a moment. You can't just [say] 'When I get there, I'll hire the smartest people and they'll tell me what to do,'" Rubio said pointedly at Trump. "There's a reason why we have civilian control of the military in this country. There's a reason why the smartest people are already there. They're already telling the president what we should be doing — he's ignoring it. You deserve to know exactly what the next commander in chief is going to do."

Toward the end of the rally before nearly 1,300, Rubio then took Trump on for recently saying that he would remain "neutral" in negotiations between Israel and Palestine. Trump told MSNBC's Joe Scarborough and Mika Brzezinski last Thursday that he would be a "neutral guy" in negotiations between the sides.

"Again, the front-runner in this race, Donald Trump, has said he's not going to take sides on Israel vs. the Palestinians because he wants to be an honest broker," Rubio railed. "Well there's no such thing as an honest broker in that because the Palestinian Authority, which has strong links to terror, teach little kids — five-year-olds — that it's a glorious thing to kill Jews."

"They turn down deal after deal after deal. They don't want a deal," Rubio said. "They've already said we want to destroy Israel ... We will not be an impartial advocate when it comes to the issue of Israel. When I'm president, we're going to take sides. We are going to be on Israel's side."

Thursday's debate in Houston will take place only five days before Super Tuesday, when 13 states, including Ted Cruz's Texas, and 595 delegates are at stake. Currently, Rubio leads in only one of those states (Minnesota), and trails both Trump and Cruz in the Lone Star State despite new polling showing him within striking distance of his GOP rivals.