They are calling it Spain's Watergate, but that is a poor comparison because Watergate was about the corruption of an individual political administration. What is happening in Spain is a bipartisan takedown of an insurgent left-wing party, working in coordination with the police, business leaders, and the mainstream media.

In 2016, the patriotic brigade turned its attentions to Podemos, whose leftist, anti-establishment message had made it a major threat to the traditional parties.

A police investigation into the supposedly illegal financing of Podemos with Iranian money was carried out, only to be shelved due to lack of evidence. The same year, Fuentes Gago was part of a police team sent to New York to meet with the former Venezuelan minister Rafael Isea, who says he was offered a Spanish passport and other perks in return for testifying that Podemos had received money from the Chávez administration. “If you help us to ensure that Podemos don’t [get into power], all the better for everyone,” Fuentes Gago said at the meeting, according to reports published by Spanish media.

The intrigue has also tainted the current Socialist government of Pedro Sánchez. Earlier this month, one of the prime minister’s advisers, Alberto Pozas, resigned just days before it emerged that in 2016, as editor of Interviú magazine, he had received a pen drive containing data, including private texts, from a phone which had been stolen from a close adviser to Pablo Iglesias.
...“How can we ask people to trust in our democracy if they can see that . . . there is a criminal network fabricating evidence to try to alter the results of elections?” said Montero, the party’s spokeswoman.

The examples above are merely a sampling. Plus those examples are actually worse when you look at the details. The levels of criminality put even the Trump Administration to shame.

On March 27 it was disclosed that the presiding judge in the trial of disgraced police commissioner José Manuel Villarejo had opened an investigation into the 2015 theft of the mobile phone of Podemos leader Pablo Iglesias’s assistant, Dina Bousselham, believing that it had been stolen by Interior Ministry officials. Private messages taken from the phone were later published by right-wing press outlets to whip up controversy over offhand comments the Podemos leader had made about a conservative TV presenter.

This was only the beginning. The following day Villajero, who is on trial for running extortion and espionage operations against political targets, admitted to spying on Iglesias as part of a “criminal” investigation, moreover insinuating that former vice premier Soraya Sáenz de Santamaría (of the right-wing Partido Popular) had been aware of the operation.
...A 2017 parliamentary inquiry found that “the investigation and persecution of political adversaries” took place with “the knowledge and consent” of the PP’s Interior Minister Jorge Fernández Díaz, citing as one example the fabrication of the so-called PISA report on illegal Podemos funding.

“This is a criminal network involving corrupt police officers, media organizations and leading business people.”
- Pablo Iglesias, leader of Podemos

The criminal smear campaign of the left-wing Podemos by the conservative party, in conjunction with the security forces, is one thing, but what sets this scandal apart is how the so-called Socialist Party conspired against Podemos.
And if that wasn't enough, this happened.

Podemos had been using a WhatsApp channel with tens of thousands of supporters in to deliver campaign messages ahead of the 28 April contest, and planned to use it to get out the vote on election day – but the channel was taken offline without warning this week.

WhatsApp, which is owned by Facebook, says Podemos had been breaking the terms of service by using the channel for automated mass messages. Podemos accepted that it had been using the channel for this purpose but said other parties had been doing so as well.

“Why have they shut down only the account of Podemos and not those of other parties doing the same?" Podemos Communications Secretary Juanma del Olmo said in a tweet.

Every level of the oligarchy is aligned against Podemos. Political parties, both right and center, multinational businesses, and what you would call the Deep State.
Unfortunately, it appears that it will pay off. According to polls, Podemos should finish no higher than 4th.