By Karen Lema and Mikhail Flores MANILA (Reuters) -Philippine senators on Tuesday voted to return an impeachment case against Vice President Sara Duterte to the lower house to clarify its constitutionality,

Prospects for a Senate trial of Philippine Vice President Sara Duterte were thrown into doubt late Tuesday, after the Senate voted to return the articles of impeachment to the House to ensure they aren’t in breach of the constitution.

The House of Representatives voted overwhelmingly in February to impeach Duterte for betrayal of public trust and high crimes, referring the case to the Senate to convene a trial. Duterte insists the impeachment is politically motivated and denies wrongdoing.