opportunist (n.)

1881, from opportunism (q.v.) + -ist. A word in Italian politics, later in France opportuniste was applied derisively to the moderate Léon Gambetta (1876), leader of the party between the monarchists and the extreme republicans. In English the word was used generally of anyone whose policy or tendency is to  seek to profit from the prevailing circumstances or take advantage of opportunities as they occur.

Once seated in the legislature Gambetta argued that all republicans—the old guard, young republicans, and even recent converts—could and should cooperate. He preached compromise and accommodation—Opportunism—in order to achieve the politically possible. He spoke against violent revolution and sought to promote peaceful reforms using legal methods, a stance that pitted him directly against the militant demagogue Henri Rochefort, who latched onto the term Opportunism as a term of abuse. [Robert Lynn Fuller, "The Origins of the French Nationalist Movement, 1886-1914"]

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Definitions of opportunist
opportunist (n.)
a person who places expediency above principle;
Synonyms: self-seeker
opportunist (adj.)
taking immediate advantage, often unethically, of any circumstance of possible benefit;
Synonyms: opportunistic / timeserving