(CNN) Embattled Japanese Prime Minister Shinzo Abe, who heads Tuesday to Mar-a-Lago for a meeting with US President Donald Trump, is in dire need of a policy win as he faces challenges abroad and protests at home.

After staking out a hawkish position on North Korea, Abe was caught on the back foot when Trump announced he was open to a summit with North Korean leader Kim Jong Un.

Tokyo's previous warnings not to trust Pyongyang have been dropped as both Washington and Seoul barreled forward with engagement. Abe is now seeking a summit with Kim for himself, rather than be further left out of North Asia's rapidly changing political situation.

While Abe had cultivated close ties with Trump, becoming the first foreign leader to meet him after his election, he has also faced disputes with the US leader over trade.

"It's a sign of the continuing close relationship that he was granted a meeting at short notice," said Euan Graham, director of the International Security Program at Australia's Lowy Institute.

"But the shine is coming off there, too, given Trump's tendency to apply leverage freely between economic and security issues."

Photo taken from a Kyodo News helicopter on April 14, 2018, shows about 30,000 people gathered in front of the Diet building to seek Prime Minister Shinzo Abe's resignation in the wake of a string of recent scandals.

Protests and polling

Tens of thousands protested outside Japan's Parliament in Tokyo on Saturday, calling Abe a liar and demanding his resignation over a corruption scandal which has dogged his premiership for months.

Abe has been forced to deny intervening in land sales to ensure preferential treatment for schools close to him and his wife.

The Prime Minister's approval rating has dropped 5.4% to 37%, according to a recent Kyodo News poll , the second-lowest since his election in 2012.

While there is little political challenge to Abe's ruling Liberal Democratic Party (LDP), his grip on power may nonetheless be slipping, as the poll showed less than a fifth of respondents, or 18.3%, backed him to remain as leader when the party holds an internal election in September, the first time support for Abe has dropped below 20%.

A protester holds a placard during a demonstration against Japan's Prime Minister Shinzo Abe on April 14, 2018.

While this weekend's protests did not come near the size of rallies in 2015 protesting Abe's push to expand the military, the combination of pressure from within the LDP and from the public has some questioning whether Abe can hold on.

Junichiro Koizumi, a former LDP Prime Minister, reportedly said this week Abe may have to stand down as leader in a matter of months.

"Abe appears unable to shake off the scandals," said Graham, though he pointed out "there was a time when serving Japanese Prime Ministers would be lucky to register more than 20% popularity ratings."

"But it is the stickiest period he has faced since returning to the premiership, without question," he said.

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Trade deal

Duncan Innes-Ker, Asia regional director at the Economist Intelligence Unit, said there was "no question" that Abe had been hurt by the ongoing scandal.

"Against this background Abe badly needs a win," he said.

The Japanese leader may be hoping that win will come at Mar-a-Lago, where, according to a statement from the White House, Trump and Abe will "explore ways to expand fair and reciprocal trade and investment ties between the United States and Japan."

Innes-Ker said Trump "could potentially offer concessions on the steel and aluminum issue or he could signal a US intention to rejoin the (Trans-Pacific Partnership)."

While "both would be seen as a triumph for Abe," he warned they would not come without concessions from Tokyo.

While Trump did surprise observers by indicating last week he may be open to rejoining the TPP -- an Obama-negotiated trade deal he once slammed -- the White House is more likely to push Tokyo to sign a bilateral deal less to Abe's liking.

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Security concerns

Since returning to the premiership in 2012, Abe has made security a key plank of his appeal. His tough response to North Korean missile testing last year was a key part of his election campaign during last year's snap election.

The eventual landslide victory in that election seemed to clear the way for Abe to push for a longtime goal of his, changing the country's post-WWII constitution to allow the Self-Defense Forces (SDF), Japan's military, to develop significant offensive capabilities.

While the constitution has hardly hampered ramped up Japanese military spending in recent months , some conservatives feel a failure to change the law could leave the SDF exposed.

Abe's hawkish posture seems to have backfired, however, with both Seoul and Washington pursuing engagement with Pyongyang.

"On North Korea, Japan now looks the most isolated of the allies. It has even tried reopening independent contacts with Pyongyang, and is conducting fence-mending diplomacy with China currently," Graham said.

"But Abe has made his choice to double down on the US Alliance, and cannot be expected to reverse course now."

One major concern in Tokyo is that a US future deal with North Korea could result in Pyongyang retaining missiles which can target Japan.

Speaking in Parliament last week , Abe said an agreement to abolish North Korea's intercontinental ballistic missile (ICBM) capabilities "has no meaning for Japan."

He said he would call on Trump to push North Korea to "also abandon short and intermediate-range missiles that put Japan within range."

However, speaking before the Senate Foreign Relations Committee on Thursday, Trump's pick for new secretary of state, Mike Pompeo, said while the US would continue to defend Japan, the point of the Trump-Kim summit was "to address the nuclear threat to the United States."

"Even South Korea is struggling to get its voice heard as the denuclearization push increasingly becomes a US-China-North Korean discussion," Innes-Ker said.

"It is not clear that any party is sidelining Japan as a conscious move, but they are certainly not reaching out to include it, and its priorities could get pushed down the list as a result."