President Donald Trump needs to score a "big hit" on the one issue that helped catapult him into the White House, and he needs it soon, say some of his staunchest supporters.

After more than 50 days in office, Trump has struggled to hit a "home-run" on immigration, the kind that would solidify his base and send a message to his enemies.

And it would seem that sanctuary cities would be a good place to start.

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Why not defund them, like yesterday? That's the question from Ann Corcoran, editor of Refugee Resettlement Watch.

"Instead, Congress is entangled in one major mess over Obamacare. And, frankly, although important, repeal of Obamacare did not motivate voters to support Trump in the way immigration restriction did," said Corcoran.

There are at least 300 sanctuary cities and counties, and one new study puts the number at closer to 500.

Steve Salvi, founder of Ohio Jobs & Justice PAC, has been tracking sanctuary cities for 10 years. He says at least 40 cities and counties have declared themselves sanctuaries since Trump issued his executive order Jan. 27.

“The trend is, I think, until he actually starts putting the squeeze to them, I suspect I’ll be adding more to the list every week,” Salvi told Lifezette. “The bigger cities are doubling down, and it’s really become a hot political issue. It’s really about the next election."

But Salvi uses a different set of criteria to define a sanctuary city from that used by the Center for Immigration Studies, which stands by its late 2016 estimate of 300.

While some jurisdictions have become sanctuaries, others such as Miami-Dade County have dropped out of that dubious club, says Jessica Vaughan, director of policy for CIS.

But regardless of the number, nobody is suggesting that large numbers of sanctuary cities are backing down.

And Trump has had a shockingly low level of support from the Republican Congress on immigration issues since assuming office on Jan. 20.

Daniel Horowitz, senior editor of Conservative Review, writes: "Look at the House GOP’s agenda since January. It has been devoid of any substance. What other majority party with control of the White House has failed to act on a single significant issue in its first 100 days? Why are they not passing bills defending Trump’s executive order, and why are they not stripping the courts of jurisdiction over immigration?"

Vaughan said Trump could score big with a punch at sanctuary cities. The way to do it is to hit them in the pocketbook, cutting grants to police departments. The sooner this happens, the better, she said, although new Attorney General Jeff Sessions is still assembling his team at the Department of Justice.

"I do hope DOJ follows through and starts blocking some of these law enforcement grants because until they do these big jurisdictions are going to keep doubling down on their sanctuary policies," Vaughan told WND. "They will not stop until somebody loses funding and then they will come around. They also could be sued in federal court. That's a fight we should be having."

But there is risk in acting too soon, before the A-team is in place.

"I think he's waiting to get his team in place at the DOJ. He's already taken on some of the very important issue of extreme vetting with his executive order, but he's going to need the best possible team in place at DOJ to succeed on this jihad against immigration enforcement that's being waged by the open-borders advocacy groups that have been filling up their coffers with money to fight this.

"I can understand why the Trump administration is waiting, because they need to get the right people in place. They can't count on the people that were put into certain positions of authority by the Obama administration. Fighting all these fights before everyone is in place is not wise. The vetting order had to be done quickly, and we've seen how that's played out."

Vaughan said her list of sanctuary cities is smaller than Salvi's because she uses a more conservative criteria.

"I try to keep it to those which are deliberately obstructing ICE or have a policy that has that result, because that's what the law says, the section of federal law that makes it a crime to harbor illegal aliens," she said. "My gut feeling is it's moving in a direction, when you look at the net effect, that there are probably fewer sanctuaries now than there were before Trump took office. But I do know a number of fairly large jurisdictions, Suffolk County, New York, for example, which have turned away from being sanctuaries."

Patience wearing thin at ALIPAC

Still, patience is wearing thin among some immigration hawks.

William Gheen, president and founder of Americans for Legal Immigration PAC, said his group is growing impatient with Trump. He sees the administration's accomplishments so far as "rather bleak" on the issue of immigration.

"We don’t just have amnesty cities. Now we have an amnesty nation. And the amnesty orders are no longer Barack Obama's amnesty orders; they're Donald Trump's amnesty orders," Gheen said.

Not only has Trump not pulled federal funding from sanctuary cities, but he has also left Obama's DACA executive order in place.

DACA is the Deferred Action for Childhood Arrivals, a policy started by the Obama administration in June 2012 that allows certain illegal immigrants who entered the country as minors to receive a renewable two-year period of amnesty from deportation and eligibility for education and other government benefits.

Gheen says ALIPAC still supports Trump and will leave its endorsement in place for at least another month.

He said ALIPAC is doing an outreach "to try to find citizens to stand with us" against legislative amnesty in Congress and White House-issued executive amnesty.

"We're still endorsing Trump," he said. "We still want him to succeed and want his immigration promises to become policy. But he's breaking his promises, and his administration is signaling that they're willing to cut a deal on immigration reform/amnesty, and that is unacceptable. So we've drawn a line in the sand. We're engaging in campaigns to warn Trump to honor his promises."

He said April 17 is the breaking point.

"If DACA amnesty has not been dropped by then, we will change our endorsement of Trump and take a more adversarial position," Gheen said.

"We're an organization that has fiercely supported Donald Trump, and we're starting to think he's full of hot air. So why wouldn't these sanctuary cities think the same thing on immigration?" he asked. "The promises he made gave him the power to defeat Bush and Clinton, and now he's in office, and our immigration hardliners like Joe Arpaio and Kris Kobach have been used politically and left out of the administration. Trump is nominating pro-amnesty people such as Alexander Acosta for Labor and others. Instead of fully and equally enforcing our laws, he apparently is continuing the exact same pro-DACA program that 26 states are suing to stop."

Overturning DACA only takes a memo, he said.

"The DACA amnesty that belonged to Obama and now belongs to Trump was created with memos, and now this president who railed against it on the campaign trail is continuing it.

"It's very important that conservatives stand up to Donald Trump on this issue immediately and fervently, and send a message that we're not going to stand with him on this," Gheen said. "He depends on his personality and the fact that so many liberals are attacking him every day. But this isn’t liberals; this is constitutionalist conservatives sounding the alarm bells here that we endorsed Donald Trump for a reason, and we expect him to live up to his promises."