President Emmanuel Macron on Wednesday received a new boost in France’s presidential election campaign after a heavyweight right-wing former minister said he would back the centrist incumbent rather than his main rival.

The announcement by Eric Woerth, labour and also budget minister in governments under president Nicolas Sarkozy, represented a new blow to the campaign of right-wing challenger Valerie Pecresse of the Republicans (LR) party who has already shown signs of flagging in the polls.

“I don’t subscribe to what the LR says,” said Woerth, adding that Macron was the best choice in the April elections to “defend the interests of France and the French”.

In a furious reaction, LR leader Christian Jacob kicked him out of the party and expressed his “disappointment” over the move.

The gesture has also raised questions about the possible stance of Sarkozy in the election, who despite being a deeply polarising figure with criminal convictions, remains a major figure for many on the right.

The latest poll by the Elabe institute for BFMTV Wednesday showed Pecresse slipping by one point to 15 percent, the latest indication that the Paris region chief has failed to capitalise the momentum from her nomination late last year.

Macron remains solid on 26 percent with far-right figures Marine Le Pen and Eric Zemmour competing with Pecresse to make the second-round run-off, it said.

While far-left leader Jean-Luc Melenchon is polling respectably on 10 percent of the vote, the Socialist mayor of Paris, Anne Hidalgo, is seen on a disastrous 1.5 percent.

Hidalgo’s ratings are beginning to raise questions about the future of the Socialists, the party of former president Francois Mitterrand who dominated France throughout the 1980s and early 1990s.

Macron, who appears to be keeping his candidacy declaration to the last minute, is hot favourite to win the election, even if analysts caution that many voters have yet to make up their minds.