President Donald Trump made a lot of promises on the campaign trail — and just 68 days in, many are already in jeopardy.

Through a combination of resistance by the courts, legislative inertia, and his own changed mind, Trump is learning the same lesson that his predecessors did at the outset of their own presidencies: Making promises in a system of checks and balances is far easier than keeping them.

Courts have blocked two different versions of the president’s temporary ban on refugee relocation and of some travel from a handful of terrorism-compromised counties. And he suffered a major blow last week when the House failed to pass an administration-backed plan to repeal and replace the Affordable Care Act.

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Another Trump promise fell by the wayside not because of obstructionism but his own changed priorities. Trump has so far left in place his predecessor’s executive order issuing work permits to illegal immigrants brought to the United States as children. That has prompted the Americans for Legal Immigration PAC to threaten to revoke its support of Trump unless he kills the program by the tax filing deadline next month.

Here is a look at five other endangered Trump promises:

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1.) Building a “great, beautiful wall” (and making Mexico pay for it). It is the promise that probably is most closely identified with Trump’s rise to power. Although he has not wavered, Congress remains lukewarm. Mexico has shown no signs of complying, and while the Trump campaign toyed with a number of ideas to induce Mexico to pay, the Trump administration has asked for $2.6 billion in funding for the wall as part of its fiscal year 2018 budget.

Some members of Congress are balking at a total cost estimated at between $12 billion and $21 billion for the construction of a complete border wall. Even if the Trump administration secures that level of funding, geographic complications and expected legal challenges by property owners whose land would be used for the wall promise to slow down the project.

2.) Reforming and cutting taxes. Candidate Trump offered an ambitious plan to slash individual and corporate tax rates. His hope was that a simpler tax code and lower rates would entice American-based companies to return the trillions of dollars in profits currently held offshore to avoid U.S. taxes. Bringing that money home would, in Trump’s eyes, reduce the trend of “corporate inversions,” in which U.S.-based companies merge with foreign firms and then relocate corporate headquarters in other countries.

But tax reform is never easy. The last major overhaul of the tax code took place in 1986 and was the result of a bipartisan effort led by President Reagan and then-Sen. Bill Bradley (D-N.J.). The partisan political environment is much more toxic now, however, meaning that Republicans likely cannot count on any help from Democrats.

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And House Speaker Paul Ryan (R-Wis.) acknowledged that tax reform will be much harder as a result of the collapse of the American Health Care Act. The Obamacare repeal would have eliminated roughly $1 trillion in taxes. Congressional Republicans hoped to use that money as part of their calculations for a tax reform package.

“Yes, this does make tax reform more difficult,” Ryan said at a news conference Friday after the bill went down in flames.

3.) Paid maternity leave. A pet project of first daughter Ivanka Trump, guaranteeing six weeks of paid maternity leave for women who do not receive it from their employers has been one of the president’s early proposals.

Theoretically, this is a plan that could win support from Democrats. But many liberals have criticized Trump’s proposal as inadequate, and other Democrats seem to prefer a scorched-earth strategy of opposing Trump on all fronts. Many, for instance, refused to applaud Trump when he proposed a massive public works program during his address to a joint session of Congress.

At the same time, many Republicans are lukewarm toward an expansion of the federal role in maternity leave policies. And then there is the cost. The Committee for a Responsible Federal Budget estimated that Trump’s plan would cost about $50 billion over 10 years.

If a bill started gaining steam in the House, it is not hard to imagine the conservative Freedom Caucus opposing it en masse.

4.) Get tough on China. Trump promised to crack down on unfair Chinese trade practices — but he has yet to take concrete action toward that goal. During the transition, he fired a shot across China’s bow by taking a phone call from the president of Taiwan, which Beijing considers a breakaway province. But after taking office, Trump reiterated America’s long-standing “one China” policy.

Trump also promised to label China a “currency manipulator” and take action to cut America’s trade deficit with the Asian giant. So, far, though, Trump has not made moves. Trump could still spring into action once he gets his trade team in place, however. The Senate has yet to confirm his nominee for U.S. trade representative, Robert Lighthizer.

The administration has also treaded cautiously on another trade-related promise: to renegotiate the North American Free Trade Agreement with Canada and Mexico. Trump so far has not given Congress 90-day notice of his intention to do that.

5.) The Iran nuclear deal. On the campaign trail, Trump railed against the pact his predecessor negotiated with Iran to prevent it from becoming a nuclear power. He called it the worst deal he had ever seen and vowed to rip it up immediately upon taking office.

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Trump has indeed taken a harder line against Iran than his predecessor. He imposed sanctions on companies connected to its ballistic missile program, prompting the Iranian regime to retaliate over the weekend with sanctions on 15 American companies.

But Trump has not actually sought to revoke the nuclear deal. Other nations were party to that agreement, meaning that even if the United States tried to reimpose sanctions, others would be unlikely to follow suit. Since Trump’s election, even critics of the deal have urged caution in trying to revoke it too quickly or without sound cause.

Trump has fulfilled some campaign-era promises. He ordered the Department of Homeland Security to resume routine enforcement of immigration. He killed the proposed Trans-Pacific Partnership trade deal. And he signed an executive order targeting federal regulations.

But in Washington, Trump should remember that losses can often attract more attention than wins.