It is cracking down on organizers by threatening them with prosecution.
The visit comes as Catalonia's regional government attempts to hold a vote on independence from Spain, which could prove challenging for USA companies who are invested in Spain and have operations in Catalonia.
Senior Spanish government officials said on Tuesday authorities had done enough to prevent a meaningful referendum as Catalonia lacked an election commission, ballot boxes, ballot papers, a transparent census and election material.
"They need to stop lying, come back to reason and accept that we will all find a place for Catalonia within Spain", he added before heading to Washington.
"But it will not be a referendum", one of the officials said on condition of anonymity.
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Catalan President Carles Puigdemont has tweeted several links to websites directing people where to vote on Sunday, but these have been taken down after a court ordered sites that facilitate such information be blocked.
For its part the Catalan regional government said the vote will go ahead and it sent out notifications to Catalans to man polling booths.
The Spanish interior ministry said the order to note the details of officials was given to police by the top state prosecutor in Catalonia.
Anyone in possession of the keys or entrance codes to a polling booth could be considered a collaborator to crimes of disobedience, malfeasance and misappropriation of funds, the order said.
Grassroots groups driving Catalonia's independence movement say they have started distributing one million ballots to be used in a referendum on secession that the Spanish government has vowed to stop.
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This has sparked protests in Barcelona and other cities.
Madrid has responded with the heavy legal artillery at its disposal to block the vote, dealing a blow to plans to hold a vote with a semblance of legitimacy.
These actions have provoked mass demonstrations and drawn accusations from Catalan leaders that the Madrid government was resorting to the repression of the Franco dictatorship.
They are accused of allegedly "disseminating a website for people to participate in a referendum declared illegal by the Constitutional Court", a police spokesman said.
"They are excluding half the population", Dastis said. He also ruled out violence, saying it wasn't "an option in Catalonia".
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The poll noted that Trump's endorsement of odd has not shown much of an effect on the race. "Ray will have a hard time". Attorney General. "Against Luther they won't even fight", he said.
"If Catalonia votes for independence, even if the vote is deemed illegal, then it could put pressure on Madrid to allow the people of the region to have a legal vote, which could increase the chance of a break up of Spain", says Brooks.