Washington, DC - Saudi Arabia's Crown Prince Mohammed bin Salman will be greeted by US President Donald Trump on Tuesday.

They'll have lunch and then we will watch as the president walks him to his car. The images will be meant to send a message the countries are united.

What matters though are the words. Diplomats in the US and abroad, and likely most people in the Gulf Cooperation Council (GCC) will be waiting to see where the president lands on the crisis.

At the beginning he not only sided with the Saudi-led blockade, he took credit for giving the group permission to impose the restrictions.

The reporting was clear at the time that his secretary of state and secretary of defence were adamant that he needed to change his stance.

It took the two awhile to prevail, but eventually, Trump came out and said it was time for it to end, and he welcomed all sides to sit down with him. He predicted then that he could solve it very quickly. That didn't happen.

Now we are going to watch three leaders individually come to the White House. First the crown prince of Saudi Arabia.

In a few weeks, we will see the Emir of Qatar at the White House followed by the leader of the United Arab Emirates.

That is why the tone that is set Tuesday will be very telling. The former Secretary of State Rex Tillerson, seen as the driving force to end the GCC crisis, is gone. He was fired, by tweet.

Millions of dollars have gone into the effort to try and influence the president and the power brokers in Washington, DC.

There is something unique though about people who want to lobby for a foreign power. Under the law, they have to register as agents of a foreign government. If the lobbying firms have a contract, they have to file those with the government. They become public records.

The amount of money that is being spent by all sides is staggering.

I spoke with Ben Freeman of the Center for International Policy. His job is to track foreign money. He says the only real winner from the GCC blockade is K Street, the term used to describe Washington, DC lobbyists.

"You can trace the strong Saudi lobby back to 9/11," Freeman said.

"Saudi was really starting to invest a lot of money in lobbying and FARA [Foreign Agents Registration Act] registered firms then and they have really increased it ever since," he added.

"They have a very entrenched lobbying network, so when they add to that already entrenched network, it gets even more powerful."

The lobbyists have to provide some of the services they provide to their clients. They arrange meetings with the power brokers in Washington, DC. They host fancy receptions and invite the influential people in the capital, including columnists and journalists.

They send talking points to reporters highlighting what they think should be the real story. They put ads on Twitter, in major newspapers and make competing television commercials run on cable news. All sides have spent millions to influence the debate and the president.

We will get a sense of whether it is having an effect in the weeks ahead.