A former member of the Christian Democracy party, then he joined the Christian Democratic Centre and subsequently the UDC, becoming the national party leader in 2002, after the election of Pierferdinando Casini as President of the Chamber of Deputies.

He unexpectedly resigned from his UDC leader position on 15 October 2005, following the approval of a new proportional electoral law by the ruling coalition the House of Freedoms, stating this was not the electoral law he actually wished.

Follini also clashed with the rest of his party on several occasions, supporting, again with Bruno Tabacci's support, Giorgio Napolitano's candidacy in the presidential election and successfully campaigning in opposition to the constitutional reform approved by the House of Freedoms in 2005, then cancelled by a referendum.

On 18 October 2006 Follini officially left UDC and announced the foundation of a new centrist movement, called Middle Italy.

On 22 May 2007 he was appointed a member of the organizing committee of the embryonic centre-left Democratic Party.