In 1929, he founded his own Vlad Țepeș League (later branded "Conservative Party"), which was instrumental in ensuring the ascendancy to the throne of King Carol II, the banished heir.

Although suspected of harboring authoritarian tendencies, Filipescu was a public critic of fascism, who supported a continental alliance against Nazi Germany and a pragmatic rapprochement with the Soviet Union.

In his final years, before his death from unsuccessful blood transfusion in Geneva, Filipescu stood out as a critic of King Carol, joining efforts with Iuliu Maniu and Nicolae Titulescu.

[15] The following year, alongside Crown Prince Carol, Ottokar Czernin, and Alexandru Davila, he took part in the wax bullet dueling competition of Sinaia, designed as marksmanship practice.

Filipescu Jr first rose to prominence during the earliest stages of World War I, when Romania was still a neutral country: in late 1914, he joined a commission headed by Colonel Vasile Rudeanu, which was tasked with negotiating arms deals in Italy, France, and Switzerland.

[26] At that stage, the Filipescus supported a Romanian alliance with the Entente nations, whereas the mainstream PC sympathized with the Central Powers; a PNL cabinet, headed by Ion I. C. Brătianu, still preserved neutrality.

[30] In June, Filipescu Jr appeared with the pro-Entente "National Action" rally at Dacia Hall, alongside guest speakers Take Ionescu, Ioan Pangal, and Nicolae Titulescu.

Accompanied by Berka,[35] Grigore followed the Romanian administration and saw action on the front, advancing to the rank of Sub-lieutenant, while also joining the Labor Party, formed in 1917 by George Diamandy and other left-wing defectors from the PNL.

[38] Around that time, Filipescu identified General Alexandru Averescu, his direct superior, as an ideal leader for a new anti-establishment, anti-PNL, political movement: popular and easily manipulated.

[55] Reportedly, he also played a part in organizing the general strike on December 25, 1918, approaching Socialist Party militant Ilie Moscovici, with an offer to challenge government censorship.

"[94] Speaking at a PP rally in Focșani before the campaign of 1928, Filipescu declared himself an enemy of "demagoguery", but also acknowledged that Romania was ripe for democracy; he also denounced the PNL's "dictatorship", and claimed to expose the government's incompetence.

[119] Again turning his attention to the West, Filipescu repeatedly asked Prime Minister Iorga to make him Ambassador to Switzerland, and also sought high offices for LVȚ figures.

[124] The group thus withdrew its support for the Iorga cabinet, explicitly rejecting its plan to tackle the Great Depression with debt relief, and defending the core tenets of economic liberalism.

[127] By 1932, the PC was losing its support base on the right, with Cantacuzino-Grănicerul and other cadres migrating toward the Iron Guard, an openly fascist movement, or trying to persuade General Ion Antonescu into reviving the Vlad Țepeș League.

[130] On October 23, 1932, supported by Maniu and the PNȚ as "government's only candidate",[131] Filipescu won a Senate seat for Vlașca County, taking 147 mayoral votes; his main rival, D. Noica of the Agrarian Union Party, only had 69.

[133] Filipescu also continued to exercise an intellectual influence over the political class with his stance on debt and, in 1933, sparked a national debate over the need to restore the country risk to more manageable levels—in practice, a push toward austerity.

[142] Filipescu was critical of Premier Duca's order to ban the Iron Guard, arguining that the movement was largely harmless, and that its ranks included at least some "enthusiastic, clear-minded youths".

[145] From his position in the Senate, Filipescu pressured Gheorghe Tătărescu's government to report on its policies after Duca's assassins had been tried and sentenced; this effort was backed by the PNȚ's Grigore Gafencu and Mihail Mora.

[146] As Conservative leader, he drafted a strategy against Carol's state of emergency, which legalized political censorship, and invited the PP, the PNȚ, the Radical Peasants' Party and the Georgist Liberals to join him in this effort.

[156] According to the French journalist Georges Oudard, the PC was a strong defender "of economic and financial orthodoxy against the temptations of a coming world", "head-turning censorship" with Filipescu's "cruel wit".

[163] At the time, he had established a society named after French Premier Louis Barthou,[164] recently assassinated by political extremist Vlado Chernozemski—an act that Filipescu saw as predictive for destruction wrought by hatred.

[166] In that context, Filipescu also began challenging the Romanian far-right's claim to an intellectual monopoly on anti-communism, arguing that war and fascism carried the added risk of making the world ripe for a communist takeover.

[170] Filipescu's condemnation of Italian, German and Portuguese participation at the funerals of Ion Moța and Vasile Marin (organized by the Iron Guard in January 1937) drew notice from the Swiss, French and Dutch press.

[181] As leader of the PNȚ's "centrist" caucus, Armand Călinescu claimed that Filipescu conspired with Jewish industrialist Max Auschnitt, with both of them coaxing Carol to accept Mihalache's candidacy.

[185] On November 13, 1937, ahead of parliamentary elections in December, the Iron Guard daily Buna Vestire resumed its attacks on Filipescu, noting: "the national-peasantist party is the only Romanian political party—other than Titulescu's ridiculous pawn, Griguță Filipescu—to call for an alliance with the Soviets.

"[186] On November 26, Maniu sent Filipescu a letter, informing him "that, since national-peasantist and conservative parties have had a similar attitude toward current topics, he has reserved a number of candidacies for him, in both Chamber and Senate".

[187] Vaida-Voevod, who had split with the PNȚ, and, as leader of the Romanian Front, allied himself with the PNL, commented at the time that only Maniu "can preserve a balance between Dr Lupu and Gr[igore] Filipescu, between extreme socialism and half-witted conservatism".

[2] In January 1938, Patria newspaper, engaging in a polemic with the Conservative Costin G. Sturdza, published allegations according to which Filipescu was acting on behalf of industrialist Oskar Kaufmann, and that he had practiced blackmail throughout his career.

In March 1938, Filipescu indefinitely suspended party activities, noting that the group was rendered irrelevant by the "great upheavals facing our continent";[138] his open letter "liberated his friends from all obligation toward either him or his politics".

[197] The Filipescu family estate in Postăvari was sold at public auction in June 1939;[198] the one at Moara Vlăsiei hosted the diplomatic corps of Vichy France, then was requisitioned for storage space.