WASHINGTON – Energized by special counsel Robert Mueller's finding of "no collusion" with Russia, President Donald Trump is relitigating a host of contentious policy battles – from health care to immigration – that could dramatically shape his reelection effort.

Trump faces a political dynamic on Capitol Hill that has not changed. Democrats, who control the House and have the power to block his initiatives, remain hostile to his agenda. But the president has ramped up his rhetoric on immigration, reopened fights over health care and storm-ravaged Puerto Rico and vowed to "fix" the crisis in Venezuela.

"Now that the Mueller report is behind them, the White House feels liberated to start putting its energy into pursuing its legislative agenda," said GOP strategist Ron Bonjean. "It's likely going to force the House Democratic leadership to stand in the way of its progress, allowing Trump to use his megaphone against them."

Eyeing the growing field of Democratic candidates seeking to unseat him in 2020, Trump returned to battleground Michigan for a rally Thursday in which he reveled in the findings from the Mueller report summary and repeatedly slammed his critics.

"The collusion delusion is over," Trump told supporters at the Grand Rapids rally, where he debuted his renewed intention to fight on several policy fronts.

Here's a look at the president's post-Mueller approach:

'Party of Health care!'

Trump shocked Republicans and Democrats this week by reopening a fight over Obamacare that many believed he already fought and lost.

A decade after the Affordable Care Act became law, Trump's administration told a federal court it would support tossing the law, reversing an earlier strategy. The president promised the GOP would become the "party of health care," but the administration has not proposed a plan in two years to save the popular aspects of the plan, like guaranteed coverage for people with preexisting conditions.

Obamacare repeal:Senate narrowly defeats 'skinny repeal' of Obamacare, as McCain votes 'no'

McCain:Senate members gasp, applaud as McCain votes no on 'skinny repeal'

Republicans revoked a central Obamacare provision that required Americans to purchase health insurance or face a tax penalty, but the party has failed to repeal the law in its entirety. And some Republicans have expressed anxiety about reopening the issue.

"We're working on a plan now," Trump, apparently undaunted by those concerns, told reporters on Thursday. "We will have a plan that's far better than Obamacare."

Immigration redux

Trump is stepping up his battle on an issue that both parties in Congress have sought to avoid: Immigration. Trump has touted early work on his proposed wall along the U.S-Mexico border and has threatened to close the southern border entirely.

In recent days, the president again has raised the prospect of closing the U.S.-Mexico border, a threat he has made previously without executing. At his rally Thursday night and in a series of tweets Friday, Trump claimed Mexico is not doing enough to stop Central American migrants from crossing the border.

The logistical challenges and potential impact of closing the U.S.-Mexico border would be enormous, experts have said.

Border:Trump threatens to close border if Mexico doesn't 'immediately stop' immigrants

Meanwhile, some aides are still in the hunt for a broader solution on immigration.

Jared Kushner, the president's son-in-law and top adviser, has been meeting with experts and stakeholders to discuss potential reforms to legal immigration, said Jessica Vaughan, director of policy studies for the Center for Immigration Studies, which supports tougher immigration laws. Kushner had tried to strike that broader deal late last year as part of the failed negotiations that led to a 35-day government shutdown.

As with health care, it's not clear there's much appetite in Congress to address immigration, particularly as the presidential election heats up.

"The Dems refuse to do what they know is necessary – amend our immigration laws," Trump wrote on Twitter on Thursday. "Would immediately solve the problem!"

Trade talks

Trump met with Republican lawmakers at the White House on Tuesday as the administration prepares to shepherd its NAFTA replacement through Congress. The new U.S.-Canada-Mexico trade deal, which the president has dubbed USMCA, needs only a simple majority to clear both chambers, but the measure faces dicey prospects in the Democrat-controlled House.

Meanwhile, the White House sent high-level officials to Beijing this week to try to negotiate a way out of the impasse with China over trade. While both sides have stepped back from the tit-for-tat trade war that roiled markets last year, many existing barriers continue to affect manufacturing and agricultural industries.

New green punching bag

The Green New Deal, Democrats' aspirational proposal to confront climate change, has become a rallying cry for Trump, who has used it as an example of how Democratic candidates are veering to the left in Trump's Washington.

The proposal calls for combating climate change by eliminating carbon emissions and shifting the economy to one powered by renewable fuels. Trump sees the policy prescriptions in the plan, blocked by a procedural vote in the Senate on Tuesday,

as a winning touchstone among his core voters.

Trump has not proposed a plan to address climate change, which he described as a "hoax" during the 2016 campaign.

"What about brilliant policies like the Green New Deal?" the president's son Donald Trump Jr. asked supporters during the Michigan rally. "What's scarier about the Green New Deal is that every mainstream Democrat leading presidential contender is like 'this is a great idea!'"

Puerto Rico aid

Trump defended his record on Puerto Rico Thursday amid reports he is reopening a debate over the amount of federal aid allocated to the island after Hurricane Maria, which made landfall in 2017.

During a meeting with Senate Republicans, Trump questioned why Puerto Rico was receiving billions of dollars in aid, according to reports. Trump has had a longstanding feud with Puerto Rican officials, including San Juan Mayor Carmen Yulín Cruz, though the issue had subsided somewhat before moving to the fore again this week.

The coverage of Trump's remarks prompted Puerto Rico Gov. Ricardo Rosselló to issue a stern warning to Trump on Thursday. "If the bully gets close, I'll punch the bully in the mouth," Rosselló told CNN in an interview. "It would be a mistake to confuse courtesy with courage."

Trump fired back in remarks at the White House.

"Puerto Rico has been taken care of better by Donald Trump than by any living human being and I think the people of Puerto Rico understand it," Trump said. "They don't know how to spend the money and they're not spending it wisely."

Contributing: Christal Hayes