Protesters carried flags in the Republican red, yellow and blue colors Sunday in the Plaza Ciebeles. They argued for a "return to democracy" so that "the power is in the hands of the people."
King Juan Carlos lost favor a year ago when he was caught on camera killing an elephant in Botswana. The incident forced him to resign as president of the World Wildlife Fund, thinkSPAIN reported.
Also stirring up scandal is the king's son-in-law, Inaki Urdangarin, who is suspected of using his royal status to secure inflated sports contracts from regional politicians for his foundation, Instituto Noos, and then directing millions of euros to other companies and offshore accounts controlled by him and his associates.
His wife, Infanta Cristina, is currently suspected of knowing her husband was using her name and status to advance his questionable business deals.
There was some speculation the king would abdicate and hand over the reins to his son, Prince Felipe, thinkSPAIN reported.
The king denied the rumors even though a recent spinal surgery has meant a long convalescence period will force him to drop out of public duties for several months.