"We do not want to give up that which we have built together".
Cautious, though, Puigdemont did not once say the word "independence" as Spain and the rest of the European Union waits to see if he declares a unilateral break from Spain after the region held a banned independence referendum on October 1.
(Picture: Lola Bou/Anadolu Agency/Getty Images) Autonomy is a highly sensitive issue in Catalonia, which saw its powers taken away under the dictatorship of General Francisco Franco.
Catalonia's administration now runs its own policing, education and healthcare.
Catalan leader Carles Puigdemont announced on October 10 that the results of the vote enabled the declaration of independence.
Rajoy is likely to announce plans to take control of Catalonia's 16,000-strong police force, the Mossos d'Esquadra, whose leader Josep Lluis Trapero could face up to 15 years in jail on sedition charges for failing to contain separatist protests ahead of the referendum.
In Spanish, he accused Madrid of "attacking democracy".
But the upper house is majority-controlled by Rajoy's ruling Popular Party and he has secured the support of other major parties, meaning they will nearly certainly go through.
Saturday's dramatic developments come a day after Madrid won powerful backing from the king and the EU.
He added pointedly: "All too often in the past the prospect of redrawing borders has been presented as a heavenly panacea that has resulted in a hellish mess".
All of the top separatist leaders, as well as Barcelona mayor Ada Colau, viewed as a non-aligned moderate, will attend.
Puigdemont says an overwhelming 90 percent backed independence in the referendum, but turnout was 43 percent as many Catalans who back unity stayed away from a vote that had been ruled illegal while others were hindered from voting by a police crackdown.
Forty percent of Catalonia's 5.5 eligible voters cast ballots in the referendum, despite a show of force by Spanish police that left almost 900 people injured ahead of the October 1 vote.
Rajoy received the backing of the head of state, King Felipe, on Friday, who said at a public ceremony that "Catalonia is and will remain an essential part" of Spain.
Although Mr Rajoy underlined he had the support of both the Socialist Party and Ciudadanos, Spain's fourth largest political grouping, the measures were described as "authoritarian and a botched job." by the left-wing Podemos coalition.
Two weeks of political limbo have already taken a toll on one of Spain's most important regional economies, with almost 1,200 companies shifting their legal headquarters elsewhere in a bid to minimise the instability.
Madrid this week cut its national growth forecast for next year from 2.6 percent to 2.3 percent, saying the standoff was creating uncertainty.