The launch of Kamala Harris’s campaign has injected newfound energy into her party with less than 100 days to go in the election cycle and raised Democrats’ hopes of winning battleground states that once seemed irretrievably lost to Donald Trump, according to a set of memos exclusively shared with the Guardian.

The memos show that Democratic parties in battleground states saw a dramatic surge in contributions and volunteer sign-ups in the past week, in addition to the Harris campaign’s record-breaking fundraising haul of $200m.

They arrive as a new poll shows Harris has gained ground against Trump in six of the seven swing states since Joe Biden dropped out of the presidential race. Conducted July 24-28, the Bloomberg News/Morning Consult poll of registered voters shows Harris leading Trump in Arizona, Wisconsin and Nevada, with a two-point advantage in each, and leading in Michigan by 11 percentage points; Trump polled ahead of Harris in Pennsylvania by four points and in North Carolina by two points, and the candidates were tied in Georgia.

The memos, which were shared by the coordinated campaign between Harris for President and the Democratic National Committee, offer further promising signs for the vice-president.

In Georgia, where Joe Biden defeated Donald Trump by just 12,000 votes or 0.2 points in 2020, more than 1,000 new volunteers signed up in the 24 hours after Harris announced her candidacy, marking the largest single-day total of the campaign. Georgia Democrats also collected $200,000, as donations to the state party increased by 320% compared with the week before.

The show of force is notable given that earlier polls indicated Trump had a solid lead in Georgia. An Emerson College poll conducted earlier this month showed Trump with a 5-point advantage over Biden, 44% to 39%, but the outlet’s most recent survey showed Harris had cut that lead down to 2 points.

“Democrats up and down the ticket are seeing unprecedented support from voters across the nation,” said Abhi Rahman, deputy communications director for the DNC. “We are confident that in these battleground states, Democrats will win at every level of the ballot in November.”

The pattern has played out in other states where Trump’s lead over Biden appeared to be growing in the weeks after the president’s disastrous debate performance. In Arizona, where Biden won by about 10,000 votes or 0.3 points in 2020, more than 2,000 new Democratic campaign volunteers signed up in the past week. The Emerson College polls conducted in the past month show that Harris slashed Trump’s lead in Arizona from 10 points to 5 points.

In the key battleground state of Wisconsin, where Biden won by 0.6 points in 2020, the state party raked in $400,000 over the past week after out-raising its Republican counterpart by a margin of 14 to 1 in the first half of the year.

Wisconsin Democrats also saw 3,500 new volunteers sign up for the campaign since Harris entered the race. More than 2,000 Wisconsin volunteers completed a shift in the past week, with at least 175,000 voters contacted. That outreach could prove decisive in a state that was decided by roughly 20,000 votes four years ago.

Before Biden withdrew from the race this month, most polls indicated he was running a close race against Trump in Wisconsin. But one particularly worrisome survey conducted for AARP in the days after the debate found Trump had a 6-point lead there. The most recent Emerson College polling showed Harris and Trump tied, 47% to 47%, in Wisconsin.

Harris’s campaign launch also seems to have motivated grassroots donors, some of whom are contributing for the first time this election cycle. Of the Harris campaign’s $200m haul, 66% came from first-time donors. In Michigan, where Biden won by roughly 3 points in 2020, the state party reported a surge in small-dollar donations over the past week, collecting $100,000 from more than 1,000 individual donors. The most recent Emerson College polling showed that Michigan remains highly competitive, with Trump at 46% and Harris at 45%.

Democrats hope the financial boon will help them regain a cash advantage in the presidential race, after Trump closed his earlier gap with Biden thanks to a fundraising blitz in recent months. The Harris campaign is already putting its new money to use with a $50m advertising push in the weeks leading up to the Democratic national convention, which will take place in Chicago next month.

But Trump is not sitting on the sidelines. On Tuesday, his campaign unveiled a new ad attacking Harris over the Biden administration’s management of the US-Mexico border while mocking the vice-president as “weak” and “dangerously liberal”.

The dueling ads foreshadowed what is expected to be a hard-fought and grueling race to the finish in the presidential contest. The two candidates have even less time than it may appear to sway the electorate, as many states will start early voting in late September or early October. In Arizona, for example, early voting begins 9 October.