If in 1898 around 15% of the elected representatives are monarchists (1.2 millions votes on about 8 millions of voters, and 11 millions on the list) but their influence is fading and decrease rapidly in the following elections.
Between the two wars the monarchist movement is mostly led by the Action Française under Charles Maurras and support the Orléans pretender (there are three main monarchist factions in France: the Legitimist who support the Bourbon-Anjou, who reign in Spain, the Orléanist who support the Orléans, descendants of Louis XIII and Louis-Philippe, and the Bonapartists).
Maurras was a prominent character in France during the interwar period, journalist, poet, politician, his ideas had a large appeal after WWI. In 1934 Action Française numbered 60k, not all where monarchists, some where antisemites or nationalists. And their journal also named L'Action Française printed 200k copies in February 1934, their record. But it was also the time, after a failed attempt to change the regime, that they started to separate in different factions. In 1937 they were disavowed by the Orléans pretender Jean (John). Before that in 1926 the Pope Pie XI had condemned the Action Française, Maurras' writings where put in the Index, and the members of the Action Française were refused the sacrements, it will last until 1939.
To put it simply after the near restauration in 1870-3 of Henri, count of Chambord, on a question of flag color, monarchism was waning in France.