Trump needs to clearly set agenda in first address to Congress: experts

Trump needs to act quickly before a crisis hits or his popularity continues to decline. If Republicans wait too long, it will be difficult to implement their policy agenda, West said.

"The most important thing Trump needs to tell Congress is what his bright lines are, what he is willing to sign, and what he would not like to see Congress pass. That would help legislators figure out their policy priorities," he said.

Dan Mahaffee, an analyst with the Center for the Study of the Presidency and Congress, told Xinhua Trump's speech before Congress is an important opportunity to reemphasize the push for economic growth and reforms to a tax system that puts the US at a disadvantage to other countries.

"With this nationally televised speech before Congress, there is an opportunity to use one of the traditional bully pulpit tools of the presidency to urge Congress to take action-particularly as the president can push for specific policies at a time when there are various proposals being debate in Congress," Mahaffee said.

U.S. presidents have traditionally pushed major legislative initiatives at this point in their presidency, and a challenge for the White House has been that controversies surrounding Trump's executive orders have required the use of his political capital.

At the same time, as Trump will also have the outline of his first federal budget prepared, he will have the foundation for his legislative approach in place, Mahaffee said.

If done right, the speech could be a major opportunity for Trump, Mahaffee said.

"For a non-traditional politician, the appearance before the joint session of Congress is one of the most powerful traditional tools in the President's tool box. In major speeches, Trump has appeared far more comfortable in campaign mode, compared to pushing specific policies," Mahaffee said.

"He will want to continue to espouse his vision for his presidency-the themes that we've seen of sovereignty, security, economic populism, and job growth-but without some policy specifics, there will continue to be competing proposals in Congress that fill the vacuum," he added.