PARIS (Reuters) - French far-right leader Marine Le Pen is confident her party will win an absolute majority in parliament, form a government and impose limits on what President Emmanuel Macron can do to support Ukraine, she said days before voting starts.

Macron will remain president after a snap legislative election on June 30 and July 7, which he called after Le Pen's National Rally (RN) trounced his centrist Together alliance in European elections, but may have to share power with his foes.

"On the choice of prime minister, the president has understood he doesn't have much of a choice, as Jordan Bardella will have a mandate from the French people," Le Pen told regional newspaper Le Telegramme de Brest, referring to her party's pick for the job of head of government.

Opinion polls consistently suggest the anti-immigrant, eurosceptic RN has a comfortable lead in terms of share of the popular vote, with a left-wing coalition in second place and Macron's centrists in third.

However, the big unknown is whether the RN can win an absolute majority of 289 seats or more in the National Assembly. The latest poll, published on Wednesday by Ifop, projected it and its allies would get 220 to 260 seats.

"How arrogant of Marine Le Pen to consider that the RN has already won the election," Deputy Foreign Minister Jean-Noel Barrot told the TV channel TF1 on Thursday.

Macron's term runs until 2027 and he cannot be forced out. France has had three periods of "cohabitation", when the president and government were from opposite political camps, in its post-war history.

Le Pen predicted Macron would find this uncomfortable, even hinting that she thought he may throw in the towel early.

"I don't know what his reaction will be. Given his arrogance, will he put up with it for long?" she said in the interview published on Le Telegramme's website late on Wednesday.

Macron has repeatedly said he would remain president until 2027, whatever the outcome of the election.

'WE'RE REASONABLE PEOPLE'

In broad terms, the French constitution gives the president wide latitude on foreign policy and defence when there is cohabitation, while the prime minister and government take the lead on domestic affairs including economic policy.

But Le Pen appeared to suggest Bardella, as prime minister, would be able to restrict Macron's margin for manoeuvre.

"For the president, being head of the military is an honorific title as it's the prime minister who holds the purse strings," she said.

"Jordan doesn't intend to pick a fight with him (Macron), but he's made the red lines clear. On Ukraine, the president will not be able to send troops."

Defence Minister Sebastien Lecornu, who has accused the RN of repeatedly changing its stance on Ukraine to the point of contradicting itself, hit back.

"The constitution is not honorific," he said in a post on X, going on to quote a 1962 address by then president Charles de Gaulle on the head of state's extensive powers.

Macron caused a diplomatic uproar in February when he said Western nations should not rule out sending troops to Ukraine to help it in its war against Russian invaders. The United States and key European allies subsequently said they had no plans to send ground troops to Ukraine.

Once considered too toxic to gain power due to its virulent anti-immigrant stance that critics say stokes racism, as well as a past history of antisemitic comments, the RN has been thoroughly rebranded by Le Pen and Bardella in recent years.

The duo have repositioned it as a champion of the working class and promote policies such as reducing the retirement age, although they have been rowing back some of their costlier proposals to allay concerns about their economic competence.

"People should stop thinking the world is going to come to an end (if we win power). We're reasonable people," said Le Pen.

The party remains strongly anti-immigrant. Its policies include reducing or cancelling welfare and healthcare access for immigrants and taking away the automatic right of children born in France to foreign-born parents to be French citizens.

Le Pen has increasingly presented immigration not just as a cultural threat to what she considers authentic French values but also as an economic burden the nation cannot afford.

"Immigration is the elephant in the room. We don't know how much it costs," she told Le Telegramme as part of remarks on how a RN government would handle France's strained public finances.

(Writing by Estelle Shirbon; Editing by Janet Lawrence)

By Dominique Vidalon and Bertrand Boucey