PHOENIX, Aug 10, 2024 (BSS/AFP) - Kamala Harris took her rapid tour of battleground states to Arizona on Friday, where she hammered opponent Donald Trump on his favorite issue of immigration, as the Republican used his only rally of the week to boost a Senate candidate.

With the presidential election day just three months away, Trump's light schedule -- a rally every four or five days -- has been contrasted with the hectic program of an opponent almost 20 years his junior, and his with own vigorous campaigning in 2016.

The 78-year-old tycoon has held just five rallies since the Republican National Convention concluded in mid-July -- one fewer than Harris is staging this week alone -- and has not announced any events at all for next week.

After stops in Pennsylvania, Michigan and Wisconsin, Harris and her new running mate Tim Walz spoke to a packed stadium in Arizona, a racially diverse state along the US border with Mexico that President Joe Biden narrowly won in 2020 by around 10,000 votes.

While mostly hewing close to the script she has used in speeches throughout the week, Harris did sharpen her attack on Trump regarding illegal border crossings.

"Donald Trump does not want to fix this problem. Be clear about that," Harris said.

"He talks a big game about border security, but he does not walk the walk."

She cited a major immigration proposal that appeared set to pass Congress after months-long bipartisan negotiations, but which failed after Trump came out against it early this year.

"Trump tanked the deal because he thought by doing that it would help him win an election. But when I am president, I will sign the bill," Harris said to cheers.

"We know our immigration system is broken, and we know what it takes to fix it, comprehensive reform that includes strong border security and an earned pathway to citizenship."

- Montana rally -

She also returned to abortion, a major issue Democrats hope will help push them over the finish line in November.

Arizona is one of several states that imposed restrictions on the procedure following the Supreme Court's 2022 reversal of the nationwide right to abortion.

Trump appointed three of the six justices that voted to overturn the nearly half-century Roe v Wade precedent, Harris noted.

"Now in over 20 states in our nation, there is a Trump abortion ban, many like Arizona, with no exceptions, even for rape or incest," she said.

While Harris was rallying with over 15,000 people in Phoenix, Trump was holding his first of the week in the northern state of Montana, where he is heavily expected to win, but a key Senate seat is also up for grabs.

The ex-president, who survived an assassination attempt at a rally last month, bristled at questions over his schedule in a hastily convened press conference Thursday at his home in south Florida.

He said he had been absent from battleground states because he was "leading by a lot and because I'm letting their convention go through," a reference to the Democratic National Convention, which doesn't end until August 22.

- New toss-ups -

Trump appeared on track to win back the White House before Joe Biden dropped out of the race on July 21, but Harris has made big gains since replacing the president at the top of the ticket and naming running mate Tim Walz.

Her rise appears to have wrongfooted Trump, who dismissed her surging polling numbers as he held court in front of journalists at his Mar-a-Lago estate for a freewheeling hour-plus news conference.

He complained about coverage of Harris's large crowds and assailed her for avoiding interviews.

And in a bizarre moment that made headlines, he related an anecdote about a helicopter near-miss that never happened, in which he appeared to confuse former San Francisco mayor Willie Brown with Jerry Brown, California's governor for most of the 2010s.

He pitched three September debates -- mixing up the dates of the showdowns he was proposing -- and attacked Harris as unintelligent and incompetent.

Former prosecutor Harris -- praised for her forensic questioning as a senator and for her performance in the vice-presidential debate in 2020 -- immediately confirmed one of the dates, an ABC News face-off on September 10.

After Arizona, Harris heads to neighboring Nevada.

Highlighting the momentum shift in the race, both states were changed this week from "lean Republican" to "toss up" by election forecaster Cook Political Report.