So the “Ted Cruz is a danger to America” response has gone from outburst to campaign strategy. Donald Trump appeared on ABC’s Good Morning America to emphasize that his threat to sue Cruz over his eligibility should be taken “very seriously.” Trump reiterated that he wants the RNC to strip Cruz’ win in Iowa, and tells George Stephanopoulos that he’s been victimized by the Bushes, too:

Republican presidential front-runner Donald Trump says he is “very seriously” considering suing GOP rival Sen. Ted Cruz.

“I’m thinking about it very seriously,” Trump told ABC News’ George Stephanopoulos on “Good Morning America” today. “I’ve never dealt with anybody who lies like him.”

He also continued to attack Jeb Bush over 9/11:

Trump also continued his criticism of former President George W. Bush for his handling of the 9/11 terrorist attacks.

“Had we had my immigration policies in effect, those people wouldn’t have been in the country for the most part,” Trump said. “I don’t know if [Bush] lied or not. I know the CIA and other agencies knew something bad was going to happen. They did nothing about it.”

The flurry of attacks certainly keeps Trump’s face in the spotlight, but there’s more to it than that. Trump seems less interested in suing Cruz than in planting seeds of doubt about his ability to withstand Democratic attacks on the issue before November if Cruz gets the nomination. There is about zero chance of this being a legal liability, but the political liability might be somewhat more significant — in the primaries, anyway, which is all Trump cares about for now. This is a hard-check-into-the-sideboards play, but Cruz isn’t exactly pulling punches on Trump any more either.

The attacks on the Bushes is more straightforward. Trump is betting that the anti-establishment anger from his base of voters can easily be directed to the GOP’s most establishment family. It’s not easy to attack Jeb’s record as governor, which was more conservative than his brother’s as president, so Trump’s going after what he sees as the weak link. And while pundits and longtime GOP leadership might be aghast at Trump’s conspiracy-theory allegations, the truth is that some of that will resonate among the disaffected who flock to Trump’s banner. The question will be whether that’s enough to get him out of South Carolina with a win, as undecided voters might get disgusted by arguments they’re more used to hearing from the hard-Left fever swamps. In a five-way race, it’s probably a safe bet. When it narrows down to a three-way race … maybe not.

Meanwhile, the one person who’s mostly avoiding the mud appears to be having a renaissance in the Palmetto State. According to Politico, Marco Rubio might be the beneficiary of the food fight:

Suddenly, a candidate known for staring past and flat-out ignoring reporters attempting to speak with him as he greets supporters was answering every last question on his campaign plane and inviting a few journalists to lunch with him and his family. Before Rubio took the stage for Saturday night’s debate here in Greenville, his first foray back onto the national stage since the debacle in Manchester a week before, his campaign went ahead and booked him on all five Sunday shows the morning after — the “full Ginsberg,” as it’s known.

The quick reboot, followed by a confident debate performance Saturday night (a CBS poll showed 32 percent of respondents thought Rubio won the night), has enabled Rubio to move beyond the “Robot Rubio” narrative before it overtook his campaign, giving voters curious after New Hampshire about which Rubio was the real one the confidence that his poor performance there had been an outlier.

“We committed to doing all five Sunday shows the day after the debate because we had confidence he’d do great,” said a top Rubio campaign adviser. “We did less debate prep before this debate because we just felt like he was ready. The key for us coming out of New Hampshire was we’ve got to let Marco be Marco.”

After a few listless days on the trail in New Hampshire after the debate, Rubio has regained his energy, confidence — and sense of humor. In describing his student loans, only paid off since he wrote his book, Rubio on Sunday delivered his standard laugh line that the autobiography is “now available in paperback.” Then, as he rarely did before, he broke the fourth wall and told the audience a secret about the performance mechanics of his routine.

“The press people have heard that joke — it works, it always works, that’s why I keep saying it!” he quipped, smiling wide as if to alert the crowd that the punch line was imminent. “If something is true and it works, you should keep saying it over and over again, right?”

A flurry of polls have come out in the last 24 hours, and all of them show Rubio either in second place or in a virtual tie for it. While the rest of the field goes negative, Rubio may well steal a march on all of them by sticking to positive themes — if they let him.